%o^-^ 


/^njBi^ 


NnKtliiCiM  iiSmmAi  STATE  UNIVERSITY  LIBRARIES 


S00833070    L 


This  book  is  due  on  the  date  indicated 
below  and  is  subject  to  an  overdue 
fine  as  posted  at  the  circulation  desk. 


EXCEPTION:  Date  due  will  be 
earlier  if  this  item  is  RECALLED. 


NATURA1 


LIBRi  ,RY 


T^ 


PLCASE   RETURN  TO 

^RNSr  J-  SCH REINER 

U.  S.  DEPARTMENT  OF  AGRICULTURE. 


^ 


*se 


BUREAU  OF  PLANT  INDUSTRY— BULLETIN  NO.  149. 


**f  T  *er, 


??r/V^b  PLEASE  RETURN  TO 

™  ERNST  J.  SCHREINER 

DISEASES  OF  DECIDUOUS  FOREST 

TREES. 


BY 

HERMANN  VON  SOHRENK, 

Formerly  Expert  in  Charge  of  the  Mississippi  Vallky 

Laboratory  of  the  Bureau  of  Plant  Industry, 

AND 

PERLEY  SPAULDING, 
Pathologist,  Investigations  in  Forest  Pathology. 


Issued  June  30,  1909. 


WASHINGTON: 

government  printing  office, 

1909. 


miTiirtAi    nroAiinnro 


BULLETINS  OF  THE  BUREAU  OF  PLANT  INDUSTRY. 

The  scientific  and  technical  publications  of  the  Bureau  of  Plant  Industry,  which  was  organized  July  1, 
1991 .  art'  issued  in  a  single  series  of  bulletins,  a  list  of  which  follows. 

ration  is  directed  to  the  fact  that  the  publications  in  this  series  are  not  for  general  distribution.  The 
Superintendent  of  Documents,  Government  Printing  Office,  Washington,  D.  C,  is  authorized  by  law  to 
sell  them  at  cost,  and  to  him  all  applications  for  these  bulletins  should  be  made,  accompanied  by  a  postal 
money  order  for  the  required  amount  or  by  cash.  Numbers  omitted  from  this  list^can  not  be  furnished. 
No.    1.  The  Relation  of  Lime  and  Magnesia  to  Plant  Growth.    1901.     Price,  10  cents. 

2.  Spermatogenesis  and  FeWridatjoh  of  Zamia.   4901.    Price,  20  cents. 

3.  Macaroni  Wheats.    1901.    Price,  20  cents. 

.  mj-T  Improvement  in  Arizona.    1901.     Price,  10  cents. 

6.  A.  List  of  American  Varieties  of  peppers.    1902.    Price,  10  cents. 

7.  The  Algerian  Durum  Wheats.    1902.     Price,  15  cents. 

9.  The  North  American  Species  of  Spartina.    1902.     Price,  10  cents. 

10.  Records  of  Seed  Distribution,  etc.    1902.     Price,  10  cents. 

11.  Johnson  Grass.    1902.     Price,  10  cents.    . 

12.  Stock  Ranges  of  Northwestern  California.    1902.     Price,  15  cents. 

13.  Range  Improvement  in  Central  Texas.    1902.     Price,  10  cents. 

15.  Forage  Conditions  on  the  Border  of  the  Great  Basin.    1902.    Price,  15  cents. 
17.  Some  Diseases  of  the  Cowpea.    1902.    Price,  10  cents. 

20.  Manufacture  of  Semolina  and  Macaroni.    1902.    Price,  15  cents. 
22.  Injurious  Effects  of  Premature  Pollination.     1902.    Price,  10  cents. 

21.  Unfermented  Grape  Must.    1902.    Price,  10  cents. 
25,  Miscellaneous  Papers.    1903.    Price,  15  cents. 

27.   Letters  on  Agriculture  in  the  West  Indies,  Spain,  etc.     1902.     Price,  15  cents. 
29.  The  Effect  of  Black-Rot  on  Turnips.     1903.     Price,  15  cents. 

31.  Cultivated  Forage  Crops  of  the  Northwestern  States.    1902.     Price,  10  cents. 

32.  A  Disease  of  the  White  Ash.     1903.     Price,  10  cents. 

33.  North  American  Species  of  Leptochloa.    1903.     Price,  15  cents. 

35.  Recent  Foreign  Explorations.    1903.    Price,  15  cents. 

36.  The  '•  Bluing"  of  the  Western  Yellow  Pine,  etc.    1903.     Price,  30  cents. 

37.  Formation  of  Spores  of  Rhizopus  Nigricans,  etc.    1903.    Price,  15  cents. 
38-  Forage  Conditions  in  Eastern  Washington,  etc.    1903.     Price,  15  cents. 
39.  The  Propagation  of  the  Easter  Lily  from  Seed.    1903.    Price,  10  cents. 
11.  The  Commercial  Grading  of  Corn.    1903.     Price,  10  cents. 

43.  Japanese  Bamboos.    1903.    Price,  10  cents. 

45.  Physiological  Role  of  Mineral  Nutrients  in  Plants.    1903.     Price,  5  cents. 

17.  The  Description  of  Wh eat  Varieties.    1903.    Price,  10  cents. 

48.  The  Apple  in  Cold  Storage.    1903.    Price,  15  cents. 

19.  I  ulture  of  the  Central  American  Rubber  Tree.    1903.     Price,  25  cents. 

■~>ii.  Wild  Rice:  Its  Uses  and  Propagation.    1903.     Price,  10  cents. 

51.  Miscellaneous  Papers.    1905.     Price,  5  cents. 

5 1.  Persian  Gulf  Dates.    1903.     Price,  10  cents. 

55.  The  Dry-Rot  of  Potatoes.    1904.    Price,  10  cents. 

56.  Nomenclature  of  the  4pple.    1905.    Price,  30  cents. 

57.  Methods  Used  for  Controlling  Sand  Dunes.    1904.    Price,  10  cents. 

58.  The  Vitality  and  Germination  of  Seeds.    1904.    Price,  10  cents. 

59.  Pasture,  Meadow,  and  Forage  Crops  in  Nebraska.    1904.     Price,  10  cents. 

60.  A  Soft  Rot  of  the  Calla  Lily.    1904.    Price,  10  cents. 
62.  Notes  on  Egyptian  Agriculture.    1904.  ■  Price,  10  cents. 
'.'.3.  Investigation  of  Rusts.    1904.     Price,  10  cents. 

til.  Destroying  Algae,  etc.,  in  Water  Supplies.    1904.     Price,  5  cents. 
65.  Reclamation  of  Cape  Cod  Sand  Dunes.    1904.    Price,  10  cents. 
07.  Range  Investigations  in  Arizona.    1904.     Price,  15  cents. 

North  American  gpe^ies  of  Agrostis,    1905.    Price,  10  cents. 
69.  American  Varieties  of  Lettuce.    1904.    Price,  15  cents. 
71).  The  Commercial  Stat  us  of  Durum  Wheal.     1904.     Price,  10  cents. 

71.  Soil  Inoculation  for  Legumes.    1905.    Price.  15  cents. 

72.  Misceilaneou  L905.     Price*  5  cents. 

73.  The  Development  of  Single-Germ  Beet  Seed.    pjii5.     Price,  10  cents. 

74.  Prickly  Pear  and  other  Cacti  as  Food  for  Stock.    1905.     Price,  5  cents. 

75.  Range  Management  in  the  State  of  Washington^    1905.     Price,  5  cents. 

76.  Copper  as  an  Algicidc  and  Disinfectant  in  Water  Supplies.    1905.    Price,  5  cents. 

77.  The  Avocado,  a  Salad  Fruit  from  the  Tropics.    1905.    Price,  5  cents. 

78.  Improving  the  Quality  of  Wheat.    1905.     Price,  10  cents. 

79.  Variability  of  Wheat  Varieties  in  Resistance  to  Toxic  Salts.    1905.    Price.  5  cents. 

[Continued  on  page  3  of  cover.] 


Jul.  149,  Bureau  of  Plant  Industry,  U.  S.  Dept.  of  Agriculture. 


Plate  I. 


A  Living  Aspen  Tree  with  Several  Sporophores  of  Fomes  igniari 


us. 


U.  S.  DEPARTMENT   OF  AGRICULTURE. 

BUREAU  OF  PLANT  INDUSTRY— BULLETIN  NO.  149. 

B.  T.  <i  ALLOW  AY.  Chitf  of  Bureati 


DISEASES  OF  DECIDUOUS  FOREST 

TREES. 


HERMANN  VON  SCHRENK, 

Formerly  Expert  in  Charge  of  the  Mississippi  Valley 

Laboratory  of  the  Bureau  of  Plant  Industry, 

AND 

PERLEY  SPAULDIXG, 
Pathologist,  Investigations  in  Forest  Pathology. 


Issued  June  30,  1909. 


WASHINGTON: 
government   printing    OFFH  ! 
1909. 


BUREAU  OF  PLANT  INDUSTRY. 


Chief  of  Bureau,  Beverly  T.  Galloway. 
Assistant  Chief  of  Bureau,  Albert  F.  Woods. 
Editor,  J.  E.  Rockwell. 
Chief  Clerk,  James  E.  Jones. 


Investigations  in  Forest  Pathology. 
scientific  staff. 

Haven  Metcalf,  Pathologist  in  Charge. 
George  G.  Hedgcock  and  Perley  Spaulding,  Pathologists. 
Carl  Hartley,  Scientific  Assistant. 


149 


LETTER  OF  TRANSMITTAL. 


U.  S.  Department  of  Agriculture, 

Bureau  of  Plant  Industry, 

Office  of  the  Chief, 
Washington,  D.  C,  February  12,  1909. 
Sir:  I  have  the  honor  to  transmit  herewith  a  paper  entitled  "Dis- 
eases of  Deciduous  Forest  Trees,"  by  Hermann  von  Schrenk,  formerly 
Expert  in  Charge  of  the  Mississippi  Valley  Laboratory  of  the  Bureau 
of  Plant  Industry,  and  Perley  Spaulding,  Pathologist,  Investigations 
in  Forest  Pathology. 

The  paper  embodies  the  results  of  several  years  of  investigation 
and  gives  a  general  account  of  the  principal  diseases  of  our  hardwood 
forest  trees.  I  recommend  that  it  be  published  as  Bulletin  Xo.  149 
of  the  series  of  this  Bureau. 

Respectfully,  B.  T.  Galloway. 

Chief  of  Bureau. 
Hon.  James  Wilson, 

Secretary  of  Agriculture. 

149  3 


CONTENTS. 


Introduction 

Environmental  diseases 0 

Smoke  and  sulphur  gases 

Unfavorable  soil  conditions 

Extreme  cold 

Injuries  caused  by  animals,  wind,  etc 

Diseases  caused  by  miscellaneous  parasitic  and  saprophytic  organisms 

Diseases  caused  by  insects 

Diseases  caused  by  parasitic  higher  plants 

Diseases  caused  by  miscellaneous  fungi 

Mildews 

Tar-spot 

Rusts : 

Sycamore  leaf-blight -u 

Leaf-spots 

Leaf-blister  fungi 

Nectria  cinnabarina - ' 

Chestnut  bark  disease 

Root-rots 

Slime-flux  diseases 

Diseases  caused  by  wound  fungi 

White  heart-rot  caused  by  Fomes  igniarius 

Nature  of  disease  caused  by  Fomes  igniarius 

Susceptibility  of  different  hosts  to  the  white  heart-rot 

Distribution  of  Fomes  igniarius 

Description  of  the  fungus 

Spread  of  the  disease 

Influence  of  environment  on  prevalence  of  white  heart-rol 

Ultimate  fate  of  diseased  trees 

Effect  of  the  fungus  on  the  wood  structure 

Preventive  measures 

Red  heart-rot  caused  by  Polyporus  sulphureus 

Piped-rot  of  oak  and  chestnut 

Soft  rot  of  oaks  caused  by  Polyporus  obtusus 

Heart-rot  caused  by  Fomes  nigricans 

Disease  caused  by  Hydnum  erinaceus 

Black  locust  disease  caused  by  Fomes  rimosus 

White  heart-rot  of  ash  caused  by  Fomes  frarinophilus 

Red  heart-rot  of  birch  caused  by  Fomes  fulvus 

Soft  heart-rot  of  catalpa  caused  by  Polystictus  I  <  rsicolor. . . 

Heart-rot  of  oaks  caused  by  Fomes  everhartii 

White-rot  caused  by  Polyporus  squamosus 

Two  sap-rots 

Decay  caused  by  Fomes  fommtarius 

Decay  caused  by  Polyporus  betulinus 


6  CONTENTS. 

Page. 

Sap-rots  of  species  of  deciduous  trees 52 

Sap-rot  caused  by  Polystictus  versicolor 53 

Sap-rot  caused  by  Polystictus  pergamen us 56 

Sap-rot  caused  by  Fomes  applanatus 58 

Decay  caused  by  Stereum  frustulosum 60 

Sap-rot  caused  by  Daedalea  quercina 61 

Other  sap-rotting  fungi 61 

Decay  of  structural  timber 62 

Causes  of  decay 62 

Factors  favoring  decay 62 

Rate  of  decay 63 

Manner  of  infection 64 

Susceptibility  to  decay 65 

Preventive  methods 66 

Bibliography 69 

Description  of  plates 76 

Index 77 

149 


ILLUSTRATIONS. 


PLATES. 

Plate  I.  A  living  aspen  tree  with  several  sporophores  of  Fames  igniarius. Frontispiece. 

II.  Fig.  1 — Cross  section  of  the  trunk  of  a  living  silver  maple  rotted  by 
Fames  igniarius.  Fig'.  2. — Cross  section  of  a  living  aspen  tree  rotted 
by  Fomes  igniarius 76 

III.  Fig.  1. — Cross  section  of  a  living  beech  tree  diseased  by  /■'■ 

arius.    Fig.  2.— cross  section  of  a  living  red  oak  tree  rotted  by  Fom*  > 
everhartii ~         76 

IV.  Fig.    1. — Fruiting   body   of   Pohjporus  sulphureus.     Fig.    2.     ( 

section  of  a  living  post  oak  tree  rotted  by  Polyporus  sulphun  us —        76 

V.  Fig.  1. — Piped-rot  of  oak.     Fig.  2. — Piped-rot  of  chestnut 76 

VI.  Fig.  1. — Cross  section  of  a  paper  birch  tree  rotted  by  Fomes  nigricans. 
Fig.  2. — An  abortive  fruiting  body  of  Fomes  nigricans  upon  a  living 

tree  of  paper  birch 76 

VII.  Fig.  1. — Cross  section  of  a  living  white  oak  tree  decayed  by  Eydnum 
erinaceus.     Fig.  2. — Fruiting  body  of  Eydnum  erinaa  us  in  a  hollow 

log 

VIII.  Fig.  1.— A  dead  beech  tree  with  sporophores  of  Fomes  fomentarius. 
Fig.   2.— Cross  section  of  a   dead  beech  tree  rotted    by    Fomes 

fomentarius 

IX.  Fig.  1.— A  dead  yellow  birch  tree  with  fruiting  body  of  Polyporus 
betulinus.     Fig.  2.— Cross  section  of  yellow  birch  tree  rotted  by 

Polyporus  betulinus 

X.  Fig.  1.— An  oak  railroad  tie  rotted  by  Daedalea  quercina.     I 

Cross  section  of  the  tie  shown  in  figure  1,  two  feet  from  the  fruiting 
body 

TEXT   FIGURES. 

Fig.  1.  Oak  trees  with  mistletoe  on  the  branches 

2.  A  black  spruce  tree  with  a  large  witches'   broom  caused  by  dwarf 

mistletoe 

3.  Spanish  moss  on  a  large  oak  tree 

4.  An  aspen  tree  with  many  dead  lateral  branches 

5.  A  living  black  oak  tree  with  a  sporophore  of  Polyporus  obtusus  growing 

out  of  the  opening  of  an  insect  burrow 

6.  An  oak  railroad  tie  with  fruiting  bodies  of  Polystictus  verswolor... . 

7.  A  living  tree  of  red  oak  the  bark  of  which  was  killed  by  fire ... 

8.  A  dead  stub  of  a  maple  tree  bearing  fruiting  bodies  of  the  sap-rot  fung 

(Fomes  applanatus) 

9.  A  piece  of  oak  timber  rotted  by  Stereumfrustulosum 

10.  Diagram  showing  relative  rate  of  decay  of  2,400  pieces  of  "hill" 

"bottom"  red  oak y 

11.  Cross  section  of  an  oak  railroad  tie  rot  ted  by  one  of  the  sap-rol  tin 

149 


B.  P.  I.— 450. 


DISEASES  OF  DECIDUOUS  FOREST  TREES. 


INTRODUCTION. 

Deciduous  forest  trees  are  affected  with  a  large  Dumber  of  different 
forms  of  disease,  some  of  which  are  daily  assuming  more  andmore 
importance.  While  it  has  been  well  known  for  many  years  thai 
there  are  such  diseases  which  are  prevalent  among  broadleaf  forest 
trees,  very  little  has  been  accomplished  up  to  the  present  time  in 
the  study  of  their  occurrence,  the  amount  of  destruction  which  they 
cause,  and  the  practical  methods  of  prevention.  In  dealing  with 
timber  tracts,  whether  they  be  wood  lots  or  larger  areas,  it  is  becom- 
ing of  increasing  importance  to  take  cognizance  of  those  factors 
which  cause  depreciation  in  value  of  the  timber  produced,  cither  by 
decreasing  the  value  of  the  wood  cut  or  by  retarding  or  preventing 
the  growth  of  the  trees  themselves.  The  various  types  of  disease 
affect  both  young  and  old  trees,  and  from  the  time  the  seedling 
starts  to  develop  until  it  has  reached  maturity  it  is  liable  to  attack 
by  one  or  more  destructive  diseases. 

In  the  present  bulletin  the  results  of  a  number  of  years'  investi- 
gation of  some  of  the  more  important  diseases  of  deciduous  trees  arc 
discussed.  No  attempt  is  made  to  include  in  this  paper  all  of  these 
diseases.  Many  are  local  in  their  distribution  and  are  as  yet  of  minor 
importance  from  a  practical  standpoint.  Many  of  them  affecl  shade 
and  ornamental  trees  rather  than  forest  trees.  All  such  are  left  for 
subsequent  discussion. 

For  the  sake  of  convenience  the  diseases  of  trees  may  be  divided 
into  several  groups.  Basing  the  classification  on  the  causes  of  dis- 
ease, they  may  be  divided  into  those  caused  by  unfavorable  envi- 
ronmental conditions,  including  smoke  or  injurious  gases,  extreme 
cold,  lightning,  excessive  water  supply,  etc.,  and  those  caused  by  liv- 
ing organisms — animals,  insects,  flowering  plants,  fungi,  and  bacteria. 
Those  fungi  which  cause  disease  may  again  be  classified  into  such  as 
grow  in  the  living  parts  of  the  tree,  including  the  leaves,  the  younger 
branches,  the  newly  formed  wood  and  bark,  and  the  living  portion 
of  the  root  system,  and  those  which  grow  on  the  dead  or  dying  parte 
of  the  tree,  including  the  heartwood  of  the  trunk,  branches,  and 
roots. 

140 


10  DISEASES   OF    DECIDUOUS   FOREST    TREES. 

ENVIRONMENTAL  DISEASES. 

In  a  bulletin  of  this  kind  it  is  impossible  to  more  than  refer  to 
certain  general  types  of  diseases  caused  by  unfavorable  environ- 
mental conditions.  Of  such  conditions  the  principal  ones  affecting 
American  broadleaf  trees  are  undoubtedly  smoke  and  injurious  gases. 

SMOKE  AND  SULPHUR  GASES. 

In  many  parts  of  the  United  States  (7,  37,  71,  109°)  extensive 
areas  of  deciduous  forest  lands  have  been  severely  injured  by  the 
action  of  smoke  or  sulphur  gases  emanating  from  paper-pulp  mills, 
copper  smelters,  coke  ovens,  and  blast  furnaces.  The  effects  of  the 
sulphur  gases  first  show  themselves  in  deciduous  trees  either  by  a 
discoloration  of  the  young  leaves,  which  ultimately  turn  mottled 
yellow  and  brown  and  finally  die,  or  by  a  gradual  shriveling  and  dry- 
ing of  the  leaves.  A  general  reduction  in  the  rate  of  growth  likewise 
takes  place,  both  in  the  length  of  the  twigs  and  in  the  amount  of 
w< »( >d  formed  by  the  trunk. 

In  both  broadleaf  trees  and  conifers  the  first  effect  of  smoke  or 
gas  injury  is  usually  seen  in  the  tops.  This  refers  especially  to  trees 
standing  together  in  a  forest  or  in  groups.  Single  trees  may  first  be 
affected  either  in  that  manner  or  throughout  the  crown  generally. 
The  leaves  in  the  top  gradually  become  smaller  and  die,  while  those 
near  the  base  may  be  perfectly  healthy.  The  smaller  twigs  in  the 
top  die  next,  then  larger  branches,  and  with  long-continued  exposure 
to  injurious  gases  the  tree  slowly  dies  downward  until  it  is  killed. 

The  extent  to  which  trees  become  diseased  as  a  result  of  the  action 
of  sulphur  gases  varies  materially  with  the  species  and  the  distance 
from  sulphur-gas  formation.  Buckhout  (7)  finds  twice  as  much  sul- 
phuric acid  in  the  leaves  of  white  oaks  grown  three-fourths  of  a  mile 
from  a  large  range  of  coke  ovens  as  occurred  in  similar  leaves  taken 
from  the  vicinity  of  the  Pennsylvania  State  College. 

The  results  of  an  extended  investigation  on  the  effect  of  smelter 
fumes  on  vegetation  were  recently  published  by  Haywood  (37),  who 
confirms  the  extensive  experience  of  European  investigators  (36,  112) 
as  to  the  killing  effect  on  vegetation  of  very  small  quantities  of  sul- 
phur dioxid  in  the  air.  Haywood  found  that  in  the  vicinity  of  the 
copper  smelters  where  his  investigations  were  carried  on  the  injury 
showed  itself  by  the  increased  sulphur  trioxid  content  of  the  foliage. 
He  found  that  the  vegetation  around  the  smelter  for  at  least  3 J 
miles  north,  9  miles  south,  2 J  miles  east,  and  from  5  to  6  miles  west 
had  been  greatly  injured.     He  suggests   that   the   gases   from   the 


a  The  serial  numbers  used  in  this  paper  refer  to  the  bibliography  which  will  be 
found  on  pages  69  to  73. 
L49 


ENVIRONMENTAL  DISEASES.  11 

smelter  can  be  condensed  so  as  to  form  sulphuric  acid,  a  readily  salable 
product. 

Different  species  of  trees  show  a  marked  difference  in  susceptibility 
to  the  action  of  sulphur  gases.  As  a  rule,  conifers  arc  killed  much 
more  readily  than  deciduous  trees.  This  may  he  explained  by  the 
facts  that  gases  are  injurious  only  to  the  leaves  .,1'  lives  and  that  lie- 
leaves  of  coniferous  trees  are  exposed  to  the  gases  for  several  yi 
while  the  leaves  of  broadleaf  trees  are  renewed  from  year  to  year. 
In  Germany,  where  many  detailed  examinations  have  been  made 
during  a  number  of  years,  Haselhoff  and  Lindan  (36)  state  thai  lie- 
oak  is  the  most  resistant  tree,  followed  closely  by  the  different  species 
of  maple  and  ash.  The  elm,  alder,  poplar,  and  linden  are  more  sus- 
ceptible, and  the  birch  and  beech  are  most  susceptible.  Baywood 
states  that  3^  miles  north  of  a  smelter  large  numbers  of  trees,  espe- 
cially pines,  were  dead. 

A  series  of  investigations  has  been  conducted  for  several  years  by 
the  senior  writer  in  another  region  where  an  extensive  mixed  forest 
has  been  severely  injured  by  sulphur  gases  emanating  from  large 
copper  smelters.  The  forest  consists  largely  of  oaks  and  pines  grow- 
ing on  an  extremely  poor  and  sterile  soil,  and  the  general  develop- 
ment of  the  forest,  even  before  the  action  of  the  sulphur  gases,  was 
very  poor.  The  different  species  of  forest  trees  showed  a  marked 
difference  in  susceptibility.  The  order  of  susceptibility,  beginning 
with  the  trees  most  easily  killed,  is  as  follows : 

White  pine  (Pinus  strobus  L.). 

Hemlock  (Tsuga  sp.). 

Scrub  pine  (Pinus  virginiana  Mill.). 

Pitch  pine  (Pinus  rigida  Mill.). 

Chestnut  oak  (Quercus  prinus  L.). 

Hickory  (Hicoria  sp.). 

Black-jack  (Quercus  marilandica  Muench.). 

White  oak  (Quercus  alba  L.). 

Post  oak  (Quercus  minor  (Marsh.)  Sargent). 

Chestnut  (Castanea  dentata  (Marsh.;  Borkh.). 

Spanish  oak  (Quercus  digitata  (Marsh.)  Sud worth). 

Scarlet  oak  (Quercus  coccinea  Muench.). 

Tulip  poplar  (Liriodendron  tulipifera  L.). 

Maple  (Acer  sp.). 

Black  gum  (Xyssa  sylvatica  Marsh.). 

This  list  pertains  to  trees  of  pole  size.  During  the  sapling  -lap1  a 
somewhat  different  series  can  be  established.  The  saplings  of  | 
oak  and  white  oak  are  less  easily  affected  than  those  of  Spanish  oak 
and  scarlet  oak.  The  degree  of  discoloration  of  the  leaves  vai 
and  this  should  be  considered  an  important  factor  in  diagnosing 
smoke  or  gas  injury.  The  following  shows  the  susceptibility  to  dis- 
coloration in  a  number  of  different  species. 

149 


12  DISEASES    OF    DECIDUOUS    FOREST    TEEES. 

Very  easily  discolored:  Black  oak  (Quercus  sp.),  hickory  (Hicoria  sp.),  scarlet  oak 
(Quercus  cocdnea  Muench.),  chestnut  (Castanea  dentata  (Marsh.)  Borkh.),  and  Spanish 
oak  (Quercus  digitata  (Marsh.)  Sud worth). 

Partially  resistant  to  discoloration:  Tulip  poplar  (Liriodendron  tulipifera  L.),  white^ 
oak  (Quercus  alba  L.),  chestnut  oak  (Q.  prinus  L.),  and  post  oak  (Q.  minor  (Marsh.) 
Sargent). 

Quite  resistant  to  discoloration:  Black  gum  (Xyssa  sylvatiea  Marsh.),  white  pine 
(Pinus  strobus  L.),  maple  (Acer  sp.).  pitch  pine  (Pinus  rigida  Mill.),  and  hemlock 
(Tsuga  sp.). 

A  great  variation  in  susceptibility  to  gas  injury  has  been  noted  by 
the  senior  writer  in  different  regions,  largely  because  the  general 
growth  conditions  have  a  direct  relation  to  the  question  of  smoke  and 
gas  resistance.  Trees  growing  in  good  soil,  not  too  close  together, 
so  that  they  grow  vigorously,  are  more  resistant  than  those  grown 
on  poorer  soils  or  crowded  together.  Whether  smoke  or  gas  has  any 
direct  influence  on  the  soil,  thereby  causing  disease  in  the  roots,  has 
not  yet  been  definitely  determined.  HaselhofT  and  Lindau  (36)  con- 
clude that  the  smoke  or  gas  has  no  influence  whatever  on  the  soil, 
while  \Vieler  (112)  cites  a  striking  instance  showing  that  soil  from  a 
smoky  district  is  very  injurious  to  healthy  trees  planted  in  it.  After 
three  years'  growth  in  soil  from  a  gas  district,  100  per  cent  of  ash.  92 
per  cent  of  maple,  72  per  cent  of  beech,  8  per  cent  of  spruce,  and  no 
oak  trees  were  dead. 

The  greatest  distance  at  which  the  sulphur  fumes  injured  trees  was 
about  3  miles,  toward  the  north  and  northwest. 

The  most  extreme  gas  injuries  usually  occur  close  to  the  source  of 
gas  production,  and  injury  diminishes  rapidly  as  the  distance  from 
this  point  increases.  The  injury  is  furthermore  greatest  in  the  direc- 
tion in  which  the  prevailing  winds  blow.  It  is  usually  most  extreme 
where  the  source  of  gas  production  is  in  confined  valleys  or  basins  (37). 

Preventive  measures  with  reference  to  gas  injury  can  often  be 
carried  out  with  much  success.  These  consist  in  the  construction 
of  tall  smokestacks  at  the  manufacturing  plant  where  the  injurious 
gases  originate,  so  as  to  carry  them  into  the  higher  strata  of  the  air. 
The  same  end  may  be  obtained  by  the  erection  of  the  manufacturing 
plant  at  the  most  elevated  point  in  any  given  region.  A  second 
method  which  has  been  used  with  more  or  less  success  in  Europe 
consists  in  bringing  about  the  condensation  of  the  gases  by  passing 
the  smoke  from  furnaces  or  kilns  through  water. 

UNFAVORABLE    SOIL    CONDITIONS. 

Under  unfavorable  soil  conditions  a  large  number  of  disease- 
causing  factors  are  usually  grouped,  most  of  which  are  but  imper- 
fectly recognized  so  far  as  their  specific  action  is  concerned.  Among 
these  may  be  mentioned  the  absence  qf  a  sufficient  amount  of  oxygen 
in  the  soil,  the  absence  of  necessary  food  substances,  the  absence  of 

t-t'i 


ENVIRONMENTAL   DISEASES.  13 

water  or  its  presence  in  excess,  the  absence  of  humus  or  its  presence 
in  excess,  and  a  generally  unfavorable  physical  make-up  of  the  soil. 
For  a  general  discussion  of  this  question  see  Galloway  and  W Is 

Different  species  of  deciduous  trees  are  affected  in  different  \ 
by  any  or  all  of  these  conditions.  Certain  species  thrive  on  flense 
clayey  soil  which  has  but  little  aeration  and  which  Is  generally  com- 
paratively free  from  vegetable  matter,  while  others  present  a  starved 
appearance  on  such  soil,  which  is  usually  recognized  in  the  tree  by  a 
dying  back  of  the  topmost  branches,  giving  rise  to  what  is  usually 
known  as  a  "stag-headed"  condition.  This  same  appearance  is 
brought  about  in  some  cases  by  an  excessive  amount  of  ground  water. 
The  beech  (Fagus  atropunicea  (Marsh.)  Sudworth),  the  tulip  poplar 
(LiriodendrontulipiferaL.) ,  and  the  true  white  oak  (Qu<  reus  alba  I ,.  a  re 
trees  which  are  particularly  sensitive  to  excessive  water  supply  in  the 
soil.  On  the  other  hand,  the  red  gum  (IAquidambar  styraciflua  L. 
overcup  oak  (Quercus  lyrata  Walt.),  and  water  oak  (Q.  aquatica  Wall .  I 
are  more  tolerant  in  this  respect. 

Most  forest  trees  demand  light  and  comparatively  porous  soils  with 
a  considerable  percentage  of  humus  material,  so  as  to  make  possible 
a  perfect  development  of  the  mycorrhizal  fungus  and  of  other  species 
of  soil  fungi  and  bacteria.  Although  we  do  not  fully  understand 
their  exact  relation  to  the  roots  of  forest  trees,  nevertheless  these 
organisms  appear  to  exercise  a  considerable  and  usually  beneficial 
influence  upon  their  general  development.  A  reduced  rate  < >f  gr<  >wth, 
pale  green,  yellowish,  or  etiolated  leaves,  and  the  development  of 
large  numbers  of  short,  sucker-like  branches  may  one  or  all  usually 
be  taken  to  indicate  a  weakened  or  diseased  condition  due  t<>  soil 
troubles.  Insufficient  room  for  root  development  constitutes  another 
very  important  factor  leading  to  a  weakened  or  diseased  condition. 

In  many  hilly  or  mountainous  regions  of  this  country  the  shallow 
soil  gives  rise  to  a  dwarfed  and  weakened  forest  growth.  No  more 
striking  picture  of  the  result  of  a  shallow  soil  as  compared  with  a  deep, 
rich  soil  can  be  found  than  in  the  difference  evident  in  the  general 
healthiness  of  the  trees  in  the  Ozark  Mountains  when  compared  with 
those  of  the  western  slope  of  the  Appalachian  Mountains.  Both  of 
these  regions  receive  a  heavy  annual  rainfall,  but  in  tin4  Ozarks  the 
hardpan  often  comes  to  within  2  feet  of  the  top  of  the  ground,  and  as 
a  result  a  stunted  and  diseased  forest  growth  develops,  while  in  the 
Appalachians  a  very  deep  soil,  rich  in  humus,  permits  an  extensive 
and  vigorous  root  development,  resulting  in  healthy,  vigorous  trees. 

EXTREME    COLD. 

Extreme  cold  may  sometimes  result  in  a  diseased  condition  <>f 
trees,  either  by  killing  roots  or  young  shoots  outright  (25,  63,  L07, 
110,  111),  or  by  causing  injuries,  such  as  frost  crack-,  in  the  trunks 

149 


14  DISEASES    OF    DECIDUOUS    FOREST    TREES. 

branches,  which  make  possible  the  entrance  of  disease-producing 
organisms  at  a  later  date.  The  winter  of  1904-5  was  characterized 
by  extreme  cold  and  resulted  in  considerable  destruction  to  forest 
trees  all  over  the  country.  Hail,  sleet,  and  snow  produce  injuries  to 
forest  trees  which  are  often  extreme ;  their  chief  importance  lies  in  the 
fact  that  they  produce  injuries  leading  to  diseases  caused  by  fungi  or 
insects  acting  upon  such  trees  at  a  subsequent  date. 

INJURIES    CAUSED    BY    ANIMALS,  WIND,  ETC. 

The  injuries  caused  by  the  biting  or  chewing  of  animals  may  be 
classed  in  the  same  category  as  the  injuries  referred  to  under  snow 
and  ice,  and  injuries  produced  by  windstorms  may  also  be  placed  in 
the  same  class.  It  is  very  rare  to  find  a  large  forest  tree  which  is 
seriously  affected  because  of  such  injuries,  except  in  the  case  of  vio- 
lent windstorms.  The  chief  importance  of  such  wounds  lies  in  the 
fact  that  they  open  up  pathways  for  destructive  forms  of  insects  or 
fungi,  which  are  referred  to  more  in  detail  hereafter.  Of  these  fac- 
tors, the  action  of  the  wind  in  breaking  off  branches  from  more  or 
less  mature  trees  must  be  considered  as  the  most  important. 

DISEASES  CAUSED  BY  MISCELLANEOUS  PARASITIC  AND  SAPRO- 
PHYTIC ORGANISMS. 

The  diseases  caused  by  parasitic  or  saprophytic  organisms  may  for 
convenience  be  divided  into  three  groups:  Those  caused  by  insects, 
those  caused  by  parasitic  higher  plants,  and  those  caused  by  fungi 
and  bacteria. 

DISEASES    CAUSED    BY    IXSECTS. 

The  disturbances  in  the  activities  of  the  living  parts  of  trees  caused 
by  insects  are  not  usually  classed  in  any  discussion  on  diseases  of 
plants,  although  the  changes  which  they  produce  undoubtedly  should 
be  considered  rather  from  the  standpoint  of  the  plant  than  from  that 
of  the  insect  causing  them.  Xo  special  reference  will  be  made  in 
this  discussion  to  any  of  the  diseases  of  broadleaf  trees  caused  by 
insects.  These  have  been  described  in  the  publications  of  the  Bureau 
of  Entomology  of  the  United  States  Department  of  Agriculture  by 
Dr.  A.  D.  Hopkins  (42,  43),  and  a  number  of  them  by  Dr.  E.  P. 
Felt  (18  to  21)  and  others  (22,  49,  66,  67,  87)  are  mentioned  in  the 
bibliography. 

DISEASES    CAUSED    BY    PARASITIC    HIGHER    PLAXTS. 

Many  species  of  deciduous  trees  are  attacked  by  the  common  mis- 
tletoe (Phoradendron  jlavescens  (Pursln  Nutt.).  This  parasite  is  very 
prevalent  from  the  vicinity  of  the  Ohio  River  southward,  and  west- 

149 


MISCELLANEOUS   PARASITIC    AND    SAPROPHYTIC    ORGANISMS.        15 


ward  to  southern  California.  Throughout  southern  Ohio,  Indiana, 
Illinois,  and  Missouri  it  is  found  chiefly  on  the  black  gum  (Nyssa 
sylvatica  Marsh.).  In  the  Southern  States  it  is  found  on  almosl  all 
species  of  deciduous  forest  trees,  including  the  sycamore  (PlatamtA 
occidentalis  L.),  elm  (Ulmus  americana  L.),  oaks  (Quercus  sp'.),  red 
gum  (Liquidambar  styraciflua  L.),  ashes  (Fraxinus  sp.),  Cottonwood 
(Populus  deltoides  Marsh.),  and  many  others  of  the  smaller  shrubby 
species  of  trees,  like  the  mesquite  (Prosopis  juliflora  (Swarl  z)  DC.). 

Where  it  is  present  in  any  large  quantity,  the  mistletoe  is  regarded 
as  a  serious  enemy  of  the  trees  upon  which  it  grows.  In  the  more  or 
less  virgin  forest 
tracts  of  the  Mis- 
sissippi Valley, 
extending  from 
southern  Missouri 
into  Arkansas  and 
northeastern  Loui- 
siana, many  tracts 
are  found  which 
are  so  badly  in- 
fested as  to  se- 
riously interfere 
w  i  t  h  the  annu  al 
rate  of  wood  accre- 
tion. In  the  ex- 
treme Southern 
States  vigorous  ef- 
forts are  being  made 
to  prevent  the  at- 
tack of  the  mistle- 
toe, which  has  be- 
come a  serious 
enemy  to  forest 
and  shade  trees  in 
southern  Louisiana 

and     Texas.         The  become  literally  covered  with  this  p 

parasite  is  distributed  from  tree  to  tree  chiefly  by  birds,  and  when 
it  has  once  obtained  a  foothold  in  any  given  region,  practically 
every  tree  in  that  locality  is  affected  by  it.  The  parasite  is  a  peren- 
nial and  gradually  absorbs  the  food  materials  from  the  branch  upon 
which  it  is  situated,  and  not  only  kills  off  that  part  of  the  branch 
toward  the  outside  of  the  tree  from  its  point  of  attachment,  but 
also  causes  the  formation  of  large  swellings,  or  tumors,  which  are 
most  characteristic  in  the  black  gum.  Figure  1  shows  the  extent 
which  the  oak  may  be  attacked  by  this  parasite. 


Seme  trees 


7Q1R9 R„l     1.10 HQ_ 


16 


DISEASES   OF    DECIDUOUS   FOREST   TREES. 


There  are  also  a  considerable  number  of  smaller  mistletoes  belong- 
ing to  the  genus  Arceuthobium  which  are  widely  distributed  through- 
out the  country.  Of  these  there  are  two  which  may  be  especially 
mentioned:  Arceuthobium  cryptopoda  Engelmann  and  A.  pusillum 
Peck.  The  former  is  known  to  occur  in  various  sections  of  the 
Rocky  Mountains  and  is  injurious  to  a  number  of  different  conifer- 
ous hosts;  the  latter  seems  to  be  an  eastern  form,  limited  more  or 
less  closely  to  the  Appalachian  Mountains,  and  is  definitely  known 

to  occur  from  the 
Canadian  border  to 
southeastern  Penn- 
sylvania. The  differ- 
ent species  of  Arceu- 
thobium resemble 
each  other  very  much 
in  their  habits  of 
growth,  their  manner 
of  seed  dispersal,  and 
their  effect  upon 
their  hosts,  so  that 
we  may  take  the 
best -known  form, 
Arceuthobium  pusil- 
lum, as  a  type  of  this 
group  (77). 

The  seeds  are 
coated  with  a  muci- 
laginous substance. 
Upon  ripening  they 
are  projected  for  sev- 
eral feet  from  the 
seed  capsules,  and 
alighting  upon  an 
adjacent  branch  or 
twig  they  stick 
tightly  to  the  bark 
and  there  germinate. 
They  may  also  be  sometimes  carried  by  birds. 

The  young  plant  pierces  with  its  holdfast  the  bark  of  the  twig  upon 
which  it  is  seated  and  establishes  communication  with  the  living  por- 
tions of  the  twig.  It  is  thus  enabled  to  feed  upon  the  sap  of  its  host, 
and  in  this  way  a  considerable  amount  of  food  material  is  diverted 
from  the  outer  end  of  the  affected  branch  to  the  parasite.  About  the 
point  of  infection  a  number  of  branchlets  develop,  and  in  the  course 
of  a  few  years  there  is  formed  a  compact,  bushy  mass  of  twigs  which 

149 


Fig.  2. 


A  black  spruce  tree  with  a  large  witches'  broom  caused  by 
dwarf  mistletoe. 


MISCELLANEOUS    PARASITIC    AND    SAPROPHYTIC    0BGANI8MB.       17 


is  known  as  a  "witches'  broom."     (See  fig.  2.)     During  the  course 
of  the  development  of  these  witches'  brooms  the  sap  becomes  diverted 
more  and  more  completely  from  the  outer  end  of  the  affected  I. ranch 
to  the  broom,  and  finally  that  part  of  the  branch  located  beyond  the 
base  of  the  parasite  dies.     These  witches'  brooms  vary  much  in  size 
being  from  only  a  few  inches  in  diameter  to  as  much  as  several  feel  in 
diameter  and  in  height.     The  distribution  of  the  seeds  is  such  thai  a 
tree  once  infected,  is  almost  sure  to  become  more  affected  as  time 
goes  on,  so  that  in  extreme  cases  there  seems  to  be  little  doubf  thai 
large   trees  may  be 
entirely  killed  by  the 
effects  of  this  plant. 
The  senior  writer  (77 ) 
has   referred  to  the 
apparent  destructive 
action  of  this  plant. 
It    is    evident    that 
the    most    practical 
method  of  eradicat- 
ing this  parasite  is  by 
cutting  all  of  the  af- 
fected treesand  burn- 
ing the  infectedparts. 
It  is  believed  that 
a    number    of    epi- 
phytic plants  some- 
times bring  about  a 
diseased  condition  of 
deciduous    trees    by 
smothering      the 
younger  leaves  and 
branches.     (See  fig. 
3.)       The    southern 
moss      ( Tillandsia 
usneoides  L.)   is  be- 
lieved by  many  to  cause  the  death  of  leaves  and   branches  of  the 
live  oak  (Quercus  virginiana  Mill.),  red  gum  (Liquidambar  styracir 
flua  L.);   and  other  deciduous    trees.      The  dense    masses    of    this 
plant  frequently  cover   the  growing  parts  of  the  tree  and  deprive 
them  of  air  and  light.     Another  species,    TiUandsia    recurvata  L., 
has  recently  been  reported  as  killing  the  live  oak  (Quercus  virginiana 
Mill.)    and   pecan    (Hicoria    pecan    (Marsh.)    Britton)    in    southern 
Texas.     In    the   Northern    States    mosses    and    lichens    frequently 
grow  in  such  profusion  that  injurious  results  follow.     Tin-  is  par- 

149 


Fig.  3.— Spanish  moss  on  a  large  oak  tree.    Note  that  the  branches 
bearing  the  moss  are  dead. 


18  DISEASES   OF    DECIDUOUS   FOREST    TREES. 

ticularly  true  of  Usnea  barbata  (L.)  Fr.  and  Ramalina  reticulata 
(Noehd.)  Krempelh.  (68).  Trelease  (100)  reports  similar  effects  due 
to  tree  mosses.  Dense  masses  of  lichens  growing  on  the  bark  of  trees 
are  described  as  injurious  by  Waugh  (105,  106),  Waite  (104),  and 
others  (44).  While  these  epiphytes  may  be  directly  responsible  for 
injuries,  and  even  death,  it  should  be  stated  that  the  evidence  in  favor 
of  such  an  assumption  is  not  very  conclusive.  It  may  be  that  these 
plants  grow  on  trees  already  weakened  by  other  factors.  No  definite 
proof  has  yet  been  brought  forward  which  would  indicate  that  leaves 
and  branches  are  killed  because  of  the  growth  of  these  plants  on  the 
branches. 

DISEASES    CAUSED    BY    MISCELLANEOUS    FUNGI. 

As  indicated  in  the  introduction,  the  fungi  which  cause  disease  may 
be  roughly  classified  into  two  groups :  Those  which  grow  on  the  living 
parts  of  trees  and  those  which  grow  on  the  dead  parts.  Of  the  forms 
growing  on  living  parts,  one  may  distinguish  in  a  general  way  between 
such  as  attack  growing  leaves  and  those  which  attack  the  living 
branches  or  wood.  Leaf  fungi  usually  attack  leaves  in  spots  and 
produce  local  disturbances  evident  as  discolored,  shriveled  spots, 
which  in  time  dry  and  break  away  entirely,  leaving  holes.  In  other 
cases  they  may  bring  about  malformations  of  the  leaves,  causing  them 
to  become  swollen  or  much  curled  and  twisted.  In  many  instances 
the  leaves  attacked  by  various  species  of  fungi  are  killed  and  prema- 
turely shed.  While  it  is  not  practicable  to  include  a  list  of  all  the 
forms  of  fungi  which  cause  leaf  diseases  of  deciduous  trees,  some  of 
the  more  important  may  be  mentioned. 


Among  those  fungi  which  attack  the  surface  of  the  leaf  are  the 
various  mildews  caused  by  the  fungi  of  the  family  Erysiphese.  These 
fungi  are  found  on  many  species  of  deciduous  forest  trees  and  are 
most  common  on  the  red  oak  (Quercus  rubra  L.),  elm  ( Ulmus  ameri- 
cana  L.),  silver  maple  (Acer  saccharinum  L.),  sycamore  (Platanus 
occidentalis  L.),  and  willow  (Salix  sp.).  They  usually  appear  during 
the  latter  part  of  the  summer,  and  because  of  their  late  appearance 
do  slight  harm,  except  where  they  attack  young  forest  trees  and 
nursery  stock.  The  small,  round,  black  fruiting  bodies  are  dotted 
here  and  there  over  the  diseased  surface  of  the  leaf  (102). 

Finely  powdered  sulphur  dusted  lightly  over  the  leaves  and  young 
twigs  will  hold  these  diseases  in  check.  This  is  very  useful  where 
small  trees  or  nursery  stock  are  to  be  treated.  The  standard  Bor- 
deaux mixture  as  well  as  any  other  of  the  efficient  fungicides  will 
control  this  trouble,  but  sulphur  is  preferable  unless  treatment  is 
wished  for  other  fungous  troubles  also. 

149 


MISCELLANEOUS    PARASITIC    AND    SAPROPHYTIC    OEGANIBM6.       19 


TAIt-NI'OT. 


The  tar-spot  disease  of  the  maple,  caused  by  Rhytisma  acerinum 
(P.)  Fr.  (34,  35,  102),  shows  as  black,  irregularly  shaped  spots  on 
the  leaves  of  different  species  of  maples  in  the  latter  part  of  the  sum- 
mer. These  black,  blister-like  spots  sometimes  (.rem-  v<t\  thickh 
scattered  over  the  leaves,  and  in  cases  where  the  attack  is  severe 
the  foliage  is  shed  prematurely  and  the  trees  weakened  thereby. 
The  fungus  causing  the  disease  develops  beneath  the  epidermis  of 
the  leaf  during  the  summer  and  forms  a  black  mass  of  mycelium. 
After  the  leaf  falls  to  the  ground  the  fungus  continues  its  develop- 
ment and  the  following  spring  produces  immense  numbers  of  spores, 
which  it  is  supposed  are  blown  by  the  wind  on  to  the  newly  formed 
leaves  of  the  second  summer. 

A  number  of  other  species  of  Rhytisma  infest  other  trees  than  the 
maples.  In  some  seasons  considerable  damage  is  done,  especially 
to  nursery  stock  of  various  ages,  in  which  case  the  appearance  is 
very  badly  marred,  both  by  the  premature  falling  of  the  leaves  and 
by  the  black  spots  upon  them  while  still  clinging  to  the  tree.  Methods 
of  prevention  consist  in  carefully  raking  the  leaves  together  and 
burning  them  in  the  fall,  thus  preventing  the  fungus  from  attaining 
maturity  the  succeeding  spring.  This  treatment  alone  if  carefully 
done  should  prevent  serious  inroads  from  this  disease. 


RUSTS. 


Deciduous  forest  trees  are  affected  only  to  a  limited  degree  by 
rust  fungi.  Now  and  then  one  finds  a  leaf-rust  (Puccinia  fraxinata 
(Lk.)  Arthur)  both  on  the  white  ash  (Fraxinus  americana  L.)  and 
green  ash  (F.  lanceolata  Borkh.),  the  telial  stage  of  which  occurs  on 
Spartina  cynosuroides  (1).  A  similar  disease  is  caused  on  the  poplar. 
willow,  and  birch  by  other  closely  related  rusts,  namely:  Melamp- 
sora  populina  (Jacq.)  Wint.  on  poplar  (Populus  deltoides  Mars 
(24),  M.  betulina  (Pers.)  Wint.  on  birch,  and  M.  saliciscapr<n  (P< 
Wint.  on  willow.  These  species  of  rust  appear  on  the  leaves  in 
early  summer  as  very  minute,  bright  yellow  spots,  which  gradually 
turn  darker  as  the  season  advances,  and  in  the  autumn  arc  almost 
black.  The  dark-colored  spores,  which  are  formed  last,  are  the 
mature  winter  spores  of  the  fungus  which  enable  it  to  live  over  the 
winter.  The  amount  of  damage  done  by  these  rusts  is  usually 
insignificant  on  large  trees,  but  in  some  seasons  when  the  weather 
conditions  are  favorable  trees  may  be  entirely  defoliated.  The 
most  extensive  damage  done  by  them  is  in  young  plantations,  this 
being  especially  true  of  the  willow  leaf-rust,  which  has  nv<\ 

149 


20  DISEASES   OF    DECIDUOUS   FOREST    TREES. 

considerable  damage  in  osier  willow  plantations  (93V  Where  the 
disease  is  destructive  the  affected  leaves  which  have  fallen  to  the 
oroimd  should  be  raked  together  and  burned. 

o 

SYCAMORE    LEAF-BLIGHT. 

The  different  species  of  sycamore,  and  more  especially  the  common 
sycamore  (Platanus  occidentalis  L.),  are  very  generally  affected 
throughout  this  country  and  Europe  by  a  leaf  and  twig  blight  caused 
by  the  fungus  Gloeosporium  nervisequum  Sacc,  which  in  its  perfect 
form  is  known  as  Gnomonia  veneta  (Sacc.  &  Speg.)  Kleb.  (45).  This 
fungus  attacks  the  young  leaves  at  about  the  time  they  reach  full 
growth.  The  attack  usually  takes  place  at  or  near  a  large  vein  of 
the  leaf,  resulting  in  the  stoppage  of  the  water  supply  of  considerable 
areas  of  the  leaf,  thus  leading  to  the  death  of  these  areas.  The 
deadened  portions  are  usually  located,  as  above  indicated,  along 
the  main  veins  of  the  leaf.  Sometimes  the  attack  is  made  on  the 
petiole  of  the  leaf  or  on  the  young  twig,  causing  the  death  of  an 
entire  leaf  or  bunch  of  leaves.  In  severe  attacks  the  leaves  are 
dropped  prematurely,  and  if  the  attacks  are  continued  with  inten- 
sity for  several  years  the  trees  become  seriously  weakened,  and  may 
even  die  outright. 

This  trouble  is  exceedingly  common  of  late  years  and  occurs  so 
universally  upon  the  sycamore  that  the  damage  is  becoming  notice- 
able, especially  upon  the  park  and  street  trees.  Raking  together 
the  fallen  leaves  and  burning  them,  pruning  out  dead  twigs  and 
branches,  and  spraying  with  Bordeaux  mixture  where  expense  is 
not  a  consideration  should  completely  control  this  trouble  (24,  35, 
102). 


LEAF-SPOTS. 


A  large  number  of  minute  forms  of  the  imperfect  fungi  belonging 
to  the  genera  Cercospora,  Phyllosticta,  Ramularia,  and  Septoria 
attack  the  foliage  of  many  of  the  deciduous  trees  and  cause  the 
so-called  ''leaf -spots."  Leaves  affected  with  these  diseases  usually 
exhibit  more  or  less  numerous  deadened  areas  of  small  size.  Early 
in  the  season  these  spots  are  apparently  sterile,  but  later  a  close 
examination  will  reveal  a  number  of  tiny  black  specks  located  near 
the  middle  of  the  area.  These  are  the  fruiting  bodies  of  the  fungus, 
in  winch  are  produced  the  spores  for  the  production  of  still  other 
colonies.  The  maple  leaf-spot  fungus  (Phyllosticta  acericola  Cook 
&  Ellis)  (24, 102)  may  be  taken  as  a  type  of  this  class  of  diseases. 
It  is  quite  common  upon  the  various  species  of  maple,  and  in  severe 
attacks  where  a  large  proportion  of  the  leaf  surface  is  affected  the 
leaves  drop  prematurely.     As  a  general  thing,  however,  these  dis- 

149 


MISCELLANEOUS    PARASITIC    AND    SAPROPHYTIC    ORGANISMS.      21 

eases  occur  locally  and  do  not  affect  the  leaves  so  seriously  as  to 
cause  them  to  fall  before  they  should  naturally.  Collecting  and 
burning  the  fallen  leaves  and  spraying  where  practicable  will  con- 
trol this  trouble. 

LEAF-BLISTER   FUNGI. 

The  leaf  -blister  fungi,  belonging  to  the  Exoascerc,  attack  the  leaves 
of  a  number  of  the  deciduous  trees  and  deform  them.  The  species 
which  is  best  known  in  this  country  is  probably  Taphrina  cat  ml* sa  ns 
(Mont.  &  Desm.)  Tul.,  which  occurs  upon  the  foliage  of  a  Dumber 
of  different  species  of  oak  in  various  parts  of  the  country  (11  1  . 
This  disease  attacks  the  newly  formed  leaves  and  causes  an  abnormal 
growth,  so  that  the  leaf  looks  as  if  blistered  over  the  affected  areas. 
The  development  of  the  fungus  is  quite  rapid,  and  in  extreme  cases 
defoliation  may  result  from  its  attacks.  The  cumulative  effeel  of 
this  disease  where  it  occurs  for  several  years  upon  the  same  trees 
may  result  in  the  death  of  the  affected  trees.  Burning  the  fallen 
leaves  and  spraying  where  practicable  will  hold  this  disease  in  check. 

NECTRIA    CINNABARIXA. 

Nectria  cinnabarina  (Tode)  Fr.  has  sometimes  been  considered  a 
parasite  (23,  27,  52,  69,  102),  but  should  really  be  considered  a  hemi- 
parasite.  Its  spores  obtain  entrance  into  branch  wounds  caused  by 
hail,  rodents,  or  birds,  and  the  resulting  mycelium  grows  through 
the  partially  weakened  wood  and  ultimately  produces  small  red 
clusters  of  fruiting  bodies.  The  stimulus  exerted  upon  some  of 
the  living  portions  of  the  cambium  layer  by  the  presence  of  the 
fungus  mycelium  frequently  accelerates  the  callus  production  at 
the  edge  of  the  wood.  The  callus  of  the  first  year  is  then  Invaded 
by  the  fungous  mycelium  and  killed,  and  a  second  layer  of  callus 
starts  to  develop.  This  may  happen  for  a  number  of  years,  until 
a  large  area  of  dead  wTood  having  the  appearance  of  a  virulent  canker 
is  formed  on  the  branch  or  trunk.  "Where  these  cankers  grow  t<>  be 
of  any  size  they  ultimately  result  in  the  death  of  the  branch,  or 
where  they  occur  on  a  young  tree,  in  the  death  of  the  tree  itself. 

There  is  a  large  group  of  the  fungi  belonging  to  the  Pyrenomycetes, 
a  number  of  which  attack  the  living  tissues  of  the  bark  and  the  wood 
of  trees  weakened  by  one  cause  or  another.     These  fungi  will  usually 
not  attack  a  vigorous  tree,  but  after  a  tree  has  been  weakened,  either 
by  unfavorable  soil  or  atmospheric  conditions  or  by  the  attack  of 
some  animal,  fungus,  or  insect,  they  gain  a  foothold  and  may  pr< 
duce  more  or  less  serious  forms  of  disease.     They  likewise  ob 
entrance    through    wounds    into    tissues    which    may    properly 
called  living  tissues.     The  members  of   the  genus    Xummularia  are 

149 


22  DISEASES   OF    DECIDUOUS   FOREST    TREES. 

good  examples  of  this  type  of  fungus.  Their  black  fruiting  bodies 
are  usually  found  on  the  dead  or  dying  wood  of  the  branches  or 
trunks  of  trees,  particularly  of  the  oaks  and  beeches. 

CHESTNUT   BARK    DISEASE. 

The  chestnut  (Castanea  dentata  (Marsh.)  Borkh.)  has  been  almost 
completely  exterminated  over  extensive  areas  adjacent  to  the  city 
of  New  York  by  a  fungus  known  as  Valsonectria  parasitica  (Murrill) 
Rehm.  (54,  55,  56,  60,  61,  62,  70).  It  causes  patches  of  the  bark  to 
die  by  attacking  the  cambium  and  other  soft  tissues  of  the  bark,  and 
extends  in  all  directions  until  the  branch  or  trunk  is  girdled.  This 
leads  to  the  death  of  those  parts  above  the  girdling,  and  in  this  way 
if  the  main  trunk  is  attacked  the  entire  tree  may  be  killed.  The 
disease  attacks  the  bark  on  the  twigs,  branches,  and  trunk  without 
respect  to  its  thickness.  How  the  fungus  gains  entrance  is  uncertain, 
but  inoculation  experiments  (60,  61)  seem  to  show  that  it  is  able  to 
enter  only  through  injuries  to  the  bark.  The  affected  bark  has  a 
blackened  appearance,  is  somewhat  shrunken,  and  after  a  time  is  apt 
to  be  thickly  covered  with  projecting  brown  or  orange  or  greenish 
yellow  colored  bodies,  which  are  about  one-sixteenth  inch  in  diameter 
at  the  base,  often  long  and  twisted  or  curled,  and  taper  to  a  slender 
tip.  These  are  the  fruiting  bodies  of  the  fungus  and  are  very  char- 
acteristic of  this  disease  when  the  weather  is  moist  enough  for  their 
formation. 

The  disease  has  already  spread  south  to  Bedford  County,  Va.,  west 
to  Lancaster  County  and  Northumberland  County,  Pa.,  and  north 
to  Massachusetts.  The  Japanese  chestnut  (Castanea  crenata  Sieb.  & 
Zucc.)  is  in  general  resistant,  although  single  trees  of  this  species  have 
taken  the  disease.  Immunity  tests  of  all  known  varieties  of  chest- 
nuts are  now  in  progress  by  this  Department  (55,  56)  No  adequate 
preventive  measures  seem  to  be  known  at  present,  so  that  this  disease 
is  an  especially  threatening  one  in  the  Eastern  States. 

A  similar  disease  has  been  noted  by  the  writers  upon  the  Spanish 
oak  (Quercus  digitata  (Marsh.)  Sudworth)  in  the  Appalachians, 
especially  in  Virginia  and  western  North  Carolina.  This  disease  is 
manifested  in  the  drooping  of  the  leaves  and  their  ultimate  drying 
up,  caused  by  a  stoppage  of  the  water  supply  in  the  branches  by  an 
apparently  undescribed  species  of  Cenangium. 

ROOT-ROTS. 

Of  the  fungi  which  attack  the  living  roots,  two  deserve  particular 
notice.  Diseases  of  the  root  system  of  broadleaf  trees  are  usually 
classed  together  under  the  term  "root-rots."  By  this  is  meant  a 
disease  which  shows  in  the  tree  tops  by  a  gradual  dying  of  the  branches 

149 


MISCELLANEOUS    PARASITIC    AND    SAPROPHYTIC    ORGANISMS.       23 

and  generally  by  a  sudden  wilting  of  the  leaves  during  the  latter  part 
of  the  spring. 

Root  diseases  may  be  caused  by  unfavorable  soil  conditions  as  well 
as  by  fungi,  but  it  has  been  the  experience  of  the  writers  that  there 
is  a  decided  difference  in  the  behavior  of  diseased  trees  where  soil 
conditions  are  responsible,  as  compared  with  diseased  trees  affected 
with  some  fungous  trouble.  In  the  former  case  the  1  ree  dies  gradu- 
ally and  the  stag-headed  condition,  together  with  a  gradual  decrease 
in  the  annual  rate  of  growth,  is  very  pronounced.  Where  fungi  are 
responsible  for  root-rot  the  trees  ordinarily  show  slight  indications  of 
the  disease  in  the  trunk  and  crown  until  it  has  ■reached  an  advanced 
stage.  They  then  usually  send  out  an  unusually  large  number  of 
leaves  and  exhibit  a  strong  tendency  to  overdevelopment  of  the 
flowers  and  fruits. 

Two  fungi  have  been  found  in  the  United  States  which  have  been 
definitely  connected  with  one  or  the  other  type  of  root-rot.  It  is 
probable  that  there  are  several  others.  While  it  is  easy  to  find  a 
fungous  mycelium  in  diseased  roots,  it  is  a  comparatively  difficult 
matter  to  determine  with  any  degree  of  certainty  that  the  fruiting 
bodies  found  near  diseased  trees  bear  any  direct  relation  to  the  myce- 
lium which  occurs  in  the  diseased  root  system. 

Only  brief  reference  can  be  made  here  to  the  manner  of  growth  and 
attack  of  the  two  root-rotting  fungi.  The  more  important  of  t hex- 
is  the  ordinary  "Hallimasch"  of  the  Germans,  or  the  so-called  honey 
mushroom  (Armillaria  mellea  (Vahl.)  Quelet)  (27,  32,  34,  35,  102 
form  of  which  may  be  what  has  been  named  Clitocybe  parasitica  by 
Wilcox  (113).  The  fruiting  bodies  of  this  fungus  usually  occur  in 
large  numbers  around  the  base  of  the  trunk  of  a  diseased  tree.  They 
are  also  found  frequently  in  dense  masses  on  and  around  dead  tree 
stumps.  The  fruiting  bodies  are  honey  colored  and  the  tops  have  a 
more  or  less  viscid  appearance,  speckled  with  white.  The  stems  are 
somewhat  swollen  at  the  base,  and  a  short  distance  below  the  pileus 
they  have  a  distinct  ring,  or  annulus.  The  gills  are  white,  and  from 
them  large  quantities  of  white  spores  are  shed,  which  frequent  ly  cover 
the  ground  around  the  fruiting  bodies,  like  a  mealy  white  powder. 

The  most  characteristic  parts  of  the  honey  mushroom  are  the 
so-called  rhizomorphs,  known  popularly  as  "shoe  string  These 

consist  of  hard,  black  strands  which  occur  singly  or  in  large  numbers, 
frequently  much  interlaced  and  branched,  extending  in  all  directions 
through  the  ground  and  along  the  roots  or  stumps  of  affected  t. 
Where  they  grow  under  the  bark  and  in  the  cambium  layer,  they 
become  much  flattened.  The  fruiting  bodies  of  the  honey  mushroom 
are  found  to  develop  at  the  ends  of  these  rhizomorph  strands. 

149 


24  DISEASES   OF    DECIDUOUS   FOREST    TREES. 

The  fungus  usually  gains  entrance  through  some  wound  in  the  root 
system,  although  it  has  been  maintained  that  it  can  penetrate  the 
bark  of  uninjured  trees.  The  young  mycelium  grows  into  the 
cambium  layer,  attacks  the  living  cells,  and  finally  completely  encir- 
cles the  base  of  the  trunk  of  an  affected  tree.  As  the  fungus  continues 
to  develop,  masses  of  the  mycelium  form  rhizomorph  strands.  The 
ultimate  effect  of  the  presence  of  the  fungus  is  to  kill  the  living  layers 
of  the  tree  near  the  ground  line,  causing  a  drying  of  the  top  and  the 
ultimate  death  of  the  entire  tree. 

The  fungus  continues  to  live  in  the  dead  root  system  and  in  the  base 
of  the  trunk  of  the  tree  for  a  number  of  years,  and  the  rhizomorphs 
are  able  to  continue  their  growth  from  root  to  root  for  some  years 
after  the  trees  have  died.  It  is  this  faculty  which  makes  this  fungus 
an  exceptionally  dangerous  one,  because  it  is  thereby  enabled  to 
spread  from  tree  to  tree  through  the  soil  with  great  readiness.  The 
writers'  observations  show  that  the  dead  pieces  of  roots  left  in  newly 
cleared  forest  land  are  sources  of  infection  for  the  roots  of  fruit  trees 
when  planted  on  such  land  a  few  years  later. 

The  second  fungus,  which  affects  trees  very  much  as  does  the  honey 
mushroom,  is  a  root  fungus  (  TlielepJiora  galactina  Fr.)  (82)  which  has 
so  far  been  found  only  on  various  species  of  oak,  particularly  the 
black  oak.  It  has  been  found  to  occur  commonly  in  various  parts  of 
the  Ozark  Mountains  in  southwestern  Missouri,  western  Arkansas, 
and  eastern  Indian  Territory.  The  long  white  strands  of  this  fungus 
penetrate  the  bark  of  oak  trees  until  they  reach  the  living  tissues. 
The  fungus  generally  attacks  the  younger  trees,  and  when  the  soil 
conditions  are  favorable  for  its  development,  considerable  areas  of 
oak  forest  may  be  killed  as  a  result  of  its  activity.  It  is  one  of  those 
forms  which  cross  from  oaks  to  fruit  trees  when  planted  on  newly 
cleared  land. 

SLIME-FLUX    DISEASES. 

A  class  of  diseases  known  as  slime-flux  diseases  should  be  referred 
to  here,  because  they  are  frequently  found  on  many  of  the  deciduous 
trees.  The  slime-flux  diseases  are  common  in  this  country  on  the  yellow 
birch  (Betula  lutea  Michx.  f.),  elm  (  Ulmus  americana  L.),  dogwood 
(Cornus  florida  L.),  apple  (Pyrus  malus  L.),  and  maples  {Acer  spp.). 
They  are  characterized  by  the  appearance  of  various  colored,  slimy 
masses  with  a  decidedly  acid  odor,  which  start  at  or  near  wounds 
caused  by  different  agencies  (23,  102).  They  make  their  appearance 
usually  early  in  the  spring  when  the  sap,  containing  more  or  less 
sugar,  flows  from  the  wounds  mentioned.  In  this  sap  a  number  of 
forms  of  algae,  bacteria,  and  fungi,  usually  associated  with  certain 
low  animal  forms,  flourish  extensively.  The  fermentive  processes 
set  up  by  one  or  all  of  these  forms  kill  the  underlying  bark  and  cam- 

149 


DISEASES    CAUSED    BY    WOUND    FUNGI.  25 

bium,  and  where  they  are  allowed  to  develop  to  any  extenl  their 
destructive  action  may  extend  completely  around  a  tree,  resulting 
in  the  death  of  branches,  and  sometimes  of  the  entire  dunk.  The 
slime-flux  diseases  can  hardly  be  considered  of  great  pracl  ical  impor- 
tance and  only  become  so  where  valuable  shade  oj  park  trees  are 
affected.  As  a  preventive  measure,  the  precautions  to  be  taken  for 
wounds,  referred  to  farther  on,  are  applicable. 

DISEASES  CAUSED  BY  WOUND  FUNGI. 
WHITE    HEART-ROT.  CAUSED    BY    FOMES    IGNIARU 

The  principal  diseases  of  deciduous  forest  trees  are  caused  by  a 
group  of  fungi  which  grow  in  the  heartwood  of  the  trees.  The  chief 
interest  which  attaches  to  the  maintenance  of  wood  lots  or  foi 
tracts  comes  from  the  fact  that  such  tracts  are  maintained  for  the 
wood  which  they  produce.  Anything,  therefore,  which  either  reduces 
the  rate  of  wood  production  or  actually  destroys  the  wood  formed  is 
of  particular  interest. 

The  fungi  which  are  responsible  for  the  decay  and  destruction  of 
the  heartwood  of  various  broadleaf  trees  are  quite  numerous. 
They  are  more  or  less  alike,  however,  as  to  their  manner  of  entrance 
into  the  tree,  their  subsequent  development,  the  production  of  their 
fruiting  bodies,  and  the  manner  of  prevention.  In  the  following, 
one  of  the  commonest  of  these  fungi,  the  so-called  "false-tinder 
fungus"  ( Fomes  igniarius '  (L.)  Gillet),  is  taken  as  a  type,  and  such 
specific  differences  as  apply  to  the  other  forms  are  given  in  the  special 
chapters  in  the  latter  part  of  this  bulletin  which  are  devoted  to  the 
more  important  of  these  wood-rotting  fungi. 

NATURE    OF   DISEASE    CAUSED    BY   FOMES   IGNIARIUS. 

The  disease  of  deciduous  trees  caused  by  the  false-tinder  fungus 
(  Fomes  igniarius)  may  be  called  the  ' '  white  hea  it  -rot . "  It  is  usually 
confined  to  the  heartwood  of  the  tree,  including  the  trunk  and  larger 
branches,  but  it  may  also  affect  the  sapwood.  As  a  result  of  the 
action  of  the  false-tinder  fungus  the  heartwood  is  changed  into  a 
whitish,  soft  substance,  which  differs  little  in  the  different  species  oH 
hosts. 

A  tree  attacked  by  the  fungus  shows  no  particular  change  in  its 
general  external  appearance  during  the  early  stages  <>l'  the  disei 
in  fact,  it  is  practically  impossible  to  recognize  a  diseased  tree  until 
the  fruiting  bodies  of  the  fungus  form  on  the  outside  of  the  trunk. 
During  the  later  stages  of  the  disease  affected  trees  can  be  recognized 
by  the  presence  of  the  fruiting  bodies  of  the  fungus,  o\'  which  there 
may  be  from  one  to  a  dozen  on  a  single  tree,  at  or  near  wound-,  branch 

149 


26  DISEASES   OF    DECIDUOUS   FOREST    TREES. 

stubs,  or  knot  holes.  When  these  fruiting  bodies  appear  it  may  be 
taken  for  granted  that  the  disease  has  progressed  within  the  trunk  in 
both  directions  for  2  or  3  feet  from  the  point  of  infection. 

The  disease  may  affect  trees  at  any  time.  In  its  final  stages  it 
brings  about  a  complete  destruction  of  the  heartwood  of  the  tree,  so 
that  it  becomes  weakened  and  liable  to  be  broken  off  by  windstorms, 
thus  terminating  the  existence  of  the  affected  tree.  Diseased  trees 
may  sometimes  be  recognized  by  the  sound  emitted  when  the  trunk 
is  pounded  on  the  outside.  While  healthy  trees  give  a  vibrant  sound, 
trees  in  the  later  stages  of  the  disease  give  a  more  or  less  deadsned 
sound.  This  is  especially  true  where,  owing  to  the  destruction  of 
the  decayed  wood  by  insects,  holes  have  been  formed.  As  a  general 
rule,  however,  the  only  safe  way  to  recognize  a  diseased  tree  is  by 
the  presence  of  the  punks  or  fruiting  bodies  on  the  outside  of  the 
trunk. 

When  cut  in  two,  the  trunk  of  a  tree  affected  with  the  white  heart- 
rot  presents  an  appearance  as  shown  in  Plate  II  and  in  Plate  III, 
figure  1,  representing  both  the  early  and  the  later  stages  of  the 
disease.  It  will  be  noted  that  the  center  of  the  tree  has  been  trans- 
formed into  a  pulpy  mass  having  an  irregular  outline.  This  mass  is 
definitely  limited  on  the  outside  by  one  or  more  narrow  black  layers. 
In  some  instances  the  wood  is  discolored  outside  of  these  black  layers. 
This  is  more  marked  in  the  poplar  than  in  any  of  the  other  hosts  of 
the  fungus.  One  of  the  most  characteristic  features  of  the  decay  of 
the  trunk  is  that  the  decayed  wood  is  confined  to  one  large  central 
mass,  differing  in  this  respect  from  the  pocket-like  destruction  brought 
about  by  several  other  wood-destroying  fungi,  notably  Stereum  frus- 
tulosum,  which  is  mentioned  later  in  this  paper. 

Trees  attacked  by  the  false- tinder  fungus  rarely  become  hollow,  for 
after  the  wood  has  become  thoroughly  decayed  by  the  fungus  it 
remains  in  the  interior  as  a  pulpy  mass.  Where  hollows  do  occur, 
they  are  caused  by  various  insects  which  bore  through  the  decayed 
wood. 

SUSCEPTIBILITY    OF    DIFFERENT    HOSTS    TO    THE    WHITE    HEART-ROT. 

The  false-tinder  fungus  is  probably  one  of  the  most  widely  dis- 
tributed forms  of  wood-destroying  fungi;  it  occurs  on  more  different 
species  of  broadleaf  trees  than  any  other  similar  fungus.  Among 
its  hosts  are  to  be  found  the  most  important  timber  trees  of  the 
deciduous  forests  of  North  America.  So  far  as  known  to  date,  the 
fungus  has  been  found  on  the  following  host  species:  Beech  (Fagus 
atropunicea  (Marsh.)  Sudworth),  aspen  (Populus  tremuloides  Michx.), 
balm  of  Gilead  (P.  halsamifera  L.),  willow  (Salix  sp.),  sugar  maple 
(Acer  saccharum  Marsh.),  red  maple  (A.  rubrum  L.),  silver  maple  (A 
saccharinum  L.),  striped  maple  (A.  pennsylvanicum  L.),  yellow  birch 

149 


DISEASES    CAUSED    BY    WOUND    FUNGI.  27 

(Betula  lutea  Michx.  f.),  butternut  (Juglans  dnerea  L.),  black  walnut 
(Juglans  nigra  L.),  oaks  (Quercus  spp.),  apple  (/>•""  /,„//,/*  L..),  and 
hickory  (Hicoriasp.).  InEurope  it  is  everywhere  prevalent  upon  the 
broadleaf  trees,  but  occurs  more  commonly  on  the  beech  (  Fagus 
sylvatica  L.),  oaks  (.Quercus  spp.),  and  alder  (Alnus  incana  Medii 

In  this  country  certain  species  are  almost  universally  affected  \\  Ltfa 
the  white  heart-rot,  irrespective  of  the  region  where  they  are  found. 
An  excellent  instance  is  the  aspen.  This  tree,  which  (72,  99)  has  I  be 
widest  range  of  any  species  of  forest  tree  in  North  America,  is  subject 
to  this  disease  very  generally.  Fomes  igniarius  has  been  found  on 
this  host  from  such  extreme  points  as  Maine,  western  (ana. la  j 
Oregon,  Colorado,  and  southern  New  Mexico. 

In  New  York  and  New  England  the  beech  has  been  found  to  be 
the  most  common  host  of  this  fungus.  Wherever  any  considerable 
amount  of  beech  timber  is  found,  white  heart-rot  is  prevalent.  In 
some  sections  as  many  as  90  to  95  per  cent  of  the  beech  I  rees  of  mer- 
chantable size  have  been  found  affected  with  this  disease.  Both  tin- 
butternut  and  the  black  walnut  are  frequently  affected.  The  oaks 
are  quite  generally  affected,  but  more  especially  those  belonging  to 
the  black  oak  group. 

A  marked  difference  in  susceptibility  is  occasionally  found  in  certain 
species  of  the  same  genus.  Thus  it  has  been  reported  thai  the  aspen 
is  more  seriously  affected  in  western  Canada  than  is  the  balm  of  Gilead 
(51).  Among  the  maples  it  has  been  found  that  the  striped  maple 
is  quite  generally  attacked  in  those  localities  where  the  disease  is 
present  in  the  same  vicinity  upon  others  of  its  host  specif-.  The 
silver  maple  seems  to  be  nearly  as  susceptible  as  the  striped  maple. 
while  the  red  maple  and  sugar  maple  are  rather  randy  affected.  The 
yellow  birch  is  even  less  frequently  attacked  than  are  the  red  or  sugar 
maples. 

DISTRIBUTION    OF   FOMES   IGNIARIUS. 

The  false-tinder  fungus  (Fomes  igniarius)  is  known  to  occur 
throughout  the  United  States.  In  general,  its  distribution  may  be 
given  as  follows:  In  North  America  it  occurs  in  Alaska,  in  various 
parts  of  Canada,  throughout  the  United  States,  and  in  the  Bahamas. 
In  South  America  it  has  been  collected  in  Surinam,  Brazil,  Argentina, 
and  Patagonia.  It  is  prevalent  throughout  Europe  from  England  to 
Russia,  and  from  Scandinavia  and  Finland  to  [taly  and  Spain.  In 
Asia  it  is  known  from  Siberia,  Japan,  the  Philippines,  and  India.  It 
also  occurs  in  Tasmania,  Australia,  Java,  \e\\  Zealand,  Admir.dtx 
Islands,  Sierra  Leone,  and  South  Africa. 

It  will  be  noted  that  these  localities  embrace  the  four  quarters  "I 
the  world.     Because  of  the  lack  of  knowledge  of  the  mycolog 
flora  of  many  countries,  no  statement  can  be  made  as  to  th< 

149 


28  DISEASES    OF    DECIDUOUS    FOREST    TREES. 

rence  of  this  fungus  in  them.  The  recent  statement  of  Schuman  and 
Lauterbach  (92)  that  it  occurs  the  world  over  can  scarcely  be  doubted. 

The  amount  of  destruction  caused  by  this  fungus  in  the  North 
American  forests  is  beyond  computation,  because  of  both  the  wide 
occurrence  of  the  fungus  and  the  large  number  of  host  species  upon 
which  it  grows.  The  loss  caused  thereby  differs  considerably  with 
the  locality  and  the  host  species.  The  greatest  losses  are  brought 
about  in  more  or  less  definitely  limited  localities.  There  are  districts 
which  are  very  badly  affected  with  this  disease,  and  others  which  are 
comparatively  free  therefrom,  which  may  be  considered  a  good 
augury  from  the  standpoint  of  prevention. 

Where  this  fungus  occurs  extensively  almost  the  entire  stand  of 
certain  species  is  frequently  found  so  badly  injured  with  the  white 
heart-rot  as  to  be  practically  worthless.  In  a  certain  area  of  decidu- 
ous forests  in  the  Adirondacks  in  the  State  of  New  York,  where  the 
timber  was  comparatively  a  mature  stand,  actual  counts  showed 
that  from  90  to  95  per  cent  of  the  otherwise  merchantable  trees  of 
beech  were  rendered  valueless  from  the  attacks  of  this  fungus.  The 
same  is  true  to  a  certain  degree  in  the  regions  where  the  aspen  is 
grown  extensively  for  pulp  wood.  In  the  New  England  States, 
Colorado,  and  New  Mexico  it  is  almost  impossible  to  find  healthy 
groves  of  aspen  which  have  attained  any  age,  because  of  the  extreme 
destruction  brought  about  by  the  false-tinder  fungus.  In  the  mature 
beech  stands  of  Texas  and  Louisiana,  where  the  trees  are  1 50  years 
old  or  more,  a  very  large  percentage  are  wholly  decayed  in  the  interior 
by  this  fungus.  (PL  II,  fig.  1.)  The  same  is  true  of  many  of  the 
tracts  of  the  Appalachian  deciduous  forests.  It  may  be  stated  that 
the  amount  of  damage  caused  by  the  white  heart-rot  is  very  great; 
and  its  wide  distribution,  together  with  the  almost  universal  suscepti- 
bility of  deciduous  trees  thereto,  make  it  the  worst  enemy  of  these 
species,  especially  during  the  period  when  they  are  approaching 
maturity. 

DESCRIPTION    OF   THE    FUNGUS. 

The  fungus  Fomes  igniarius  has  been  known  for  a  great  many  years 
and  has  been  made  the  subject  of  a  large  number  of  descriptions,  as  a 
result  of  which  a  very  extensive  bibliography  has  developed,  which  is 
too  bulky  to  be  here  included.  It  is  probably  one  of  the  oldest  fungi 
known,  as  ft  attracted  attention  in  the  early  days  because  of  its  size 
and  uses.     Lightfoot  (47)  in  1777  made  the  following  statement: 

An  excellent  touchwood  is  made  from  this  fungus,  by  first  paring  off  the  outer  rind, 
then  boiling  the  remainder  in  lye,  and  afterwards  drying  and  pounding  with  a  hammer, 
or  else  pounding  and  boiling  it  up  with  saltpeter.  The  same  fungus  beaten  into  soft 
square  pieces  is  well  known  to  surgeons  by  the  name  of  Agaric,  and  has  been  much 
celebrated  for  stopping  the  bleeding  of  arteries;  it  has  not,  however,  proved  altogether 

149 


DISEASES    CAUSED    BY    WOUND    FUNGI.  29 

successful  unless  in  the  smaller  vessels.     We  are  inform. -.1  by  Gleditsch  thai  in  Fran 
conia  he  has  seen  these  beaten  pieces  of  Boletus  which  resembled  the  Boftesl  leather 
curiously  sewed  together  and  made  into  garments. 

The  false-tinder  fungus  has  been  well  known  in  Europe  for  about 

two  hundred  years.     Its  synonymy  is  given  below : 

Boletus  igniarius,  Linnseus,  C,  Species  Plantarum,  p.  1176.     1753. 
Polyporus  igniarius,  Fries,  E.,  Syst.  Mycol.,  vol.  1,  p.  375.     1821. 
Fomes  igniarius,  Gillet,  C.  C,  Champ.  France,  vol.  1,  p.  687,  pi.  156.     1  - 
Phellinus  igniarius,  Quelet,  L.,  Enchir.  Fung.,  p.  172.     18? 

Mucronoporus  igniarius,    Ellis,  J.  B.,  and  Everhart,  B.  M.,  Jour    Mycol     vrol    5 
p.  91.     1889. 
Pyro polyporus  igniarius,  Murrill,  W.  A.,  Jour.  Mycol.,  vol.  9,  p.  KM .     1903 

The  name  Fomes  igniarius  has  been  accepted  and  is  in  general  use, 
while  the  three  later  generic  names  are  not  so  well  known  or  bo  gen- 
erally accepted.  It  seems  best  to  use  the  more  common  and  better 
known  name  in  the  present  account  of  this  fungus. 

The  false-tinder  fungus  {Fomes  igniarius)  is  one  of  the  most  con- 
spicuous of  the  so-called  punks,  or  shelf  fungi,  which  grow  upon  living 
trees.  It  varies  much  in  shape,  size,  and  color,  depending  upon  its 
age  and  upon  the  species  of  tree  upon  which  it  grows.  It  is  commonly 
more  or  less  hoof  shaped,  measuring  about  as  much  in  thickness  as  in 
width.  Its  size  varies  from  1  or2  inches  to  12  inches  or  more  in  width. 
The  upper  surface  is  smooth  in  the  younger  forms  and  becomes 
concentrically  marked  as  the  fungus  grows  older.  It  is  characterized 
by  a  very  hard  external  layer,  which  is  at  first  brown,  gradually 
becoming  black,  and  in  the  older  forms  is  considerably  roughened 
and  cracked.  The  cracks,  however,  rarely  penetrate  far  into  the 
mass  of  the  sporophore.  The  sporophores  are  very  woody  and  of  a 
rusty  brown  color  on  the  inside.  The  pores  are  formed  in  Layers,  one 
below  the  other,  and  the  sporophores  apparently  may  grow  to  ;i 
great  age.  The  writers  have  found  them  with  50  layers.  Atkinson 
(4)  reports  one  with  80  layers.  The  average  number  is  from  1  •">  to  30 
layers,  presumably  indicating  an  age  of  approximately  tin-  same 
number  of  years.  The  lower  surface  is  gray  to  red-brown  in  color, 
varying  according  to  the  season.  The  edge  is  yellowish  brown  when 
first  formed,  and  very  much  lighter  in  color  than  the  top.  Toward 
the  end  of  the  season  the  newly  formed  portion  weathers  considerably 
above  and  has  a  rusty' appearance.  Although  there  i-  considerable 
variation  in  the  form  of  the  sporophore,  its  general  characteristics  are 
so  decided  that  it  is  rarely  confounded  with  any  of  the  other  wound 
fungi. 

SPREAD    OF   THE    DISEASE. 

The  white  heart-rot,  as  has  been  stated,  is  caused  by  the  growth 
and  development  in  the  w^ood  of  the  trees  of  the  mycelium  <>f  F 

149 


30  DISEASES    OF    DECIDUOUS    FOREST    TREES. 

igniarius.  The  fungus  gains  entrance  into  the  trunk  of  the  tree 
through  some  wound;  in  other  words,  it  is  a  wound  parasite  of  the 
most  distinct  type.  An  examination  of  thousands  of  infected  trees 
has  shown  without  exception  that  there  must  be  some  wound  before 
infection  will  take  place.  A  careful  series  of  observations  has  further- 
more shown  that  the  point  of  entrance  is  usually  indicated  some  years 
later  by  the  location  of  the  oldest  sporophores.  These  sporophores 
are  usually  situated  on  old  branch  stubs  or  in  holes  left  when  the  base 
of  the  branch  rotted  away. 

In  a  large  percentage  of  cases  infection  takes  place  through  old 
branch  stubs.  The  spores  of  the  false-tinder  fungus  germinate  on  a 
stub,  and  the  hypha3  grow  down  through  the  wood  of  the  stub  until 
they  reach  the  heartwood  of  the  main  trunk;  from  this  point  they 
grow  both  up  and  down  in  the  heartwood,  usually  starting  near  the 
pith,  and  advance  concentrically  outward.  The  destruction  of  the 
wood  follows  very  shortly  after  the  entrance  of  the  mycelium  into  the 
trunk,  progressing  both  outward  and  up  and  down  as  long  as  the  tree 
lives.  The  time  which  elapses  between  the  injuring  of  a  tree  and 
infection  necessarily  varies,  depending  chiefly  upon  the  presence  of 
spores  and  climatic  conditions. 

The  formation  of  sporophores  takes  place  usually  at  the  point 
where  infection  originally  occurred.  This  can  readily  be  proved  by 
an  examination  of  the  diseased  area  within  the  trunk,  especially 
during  the  early  stages  of  the  disease.  The  formation  of  sporophores 
subsequent  to  that  of  the  first  one  is  determined  by  the  location  of  the 
tree,  the  climatic  conditions,  the  size  and  vigor  of  the  tree  attacked, 
and  the  number  of  side  branches  which  may  permit  the  growth  of  the 
mycelium  from  the  center  to  the  outside,  thereby  making  possible  the 
formation  of  additional  sporophores.  The  number  of  sporophores 
which  will  form  on  a  tree  is  largely  determined  by  the  latter  fact. 
Thus,  in  the  aspen,  in  which  wounds  made  by  the  dying  of  the  lower 
branches  are  healed  over  with  difficulty,  the  number  of  sporophores  is 
very  much  larger  on  an  individual  tree  than  is  the  case  with  trees 
which  heal  over  such  wounds  more  rapidly,  like  the  beech  and  the  sugar 
maple.  It  is  not  uncommon  to  find  a  diseased  poplar  tree  with  any- 
where from  three  to  twelve  sporophores  on  various  parts  of  an  affected 
trunk  (PL  I) ;  in  the  beech  and  birch  a  smaller  number  is  the  rule. 

The  growth  of  the  mycelium  of  the  fungus  is  usually  confined  to  the 
heartwood  of  the  trees.  Hartig  states  that  the  fungus  may  enter 
trees  by  means  of  slight  wounds  in  the  sapwood,  and  describes  the 
manner  in  which  the  fungus  starts  its  development  in  the  sapwood, 
growing  from  the  sapwood  into  the  heart.  His  observations  refer  to 
the  oak,  however,  with  which  comparatively  little  work  has  been 
done  in  this  country. 

149 


DISEASES    CAUSED    BY    WOUND    FUNGI.  31 

After  the  fungus  has  once  obtained  a  start  in  the  wood  of  the  trunk 
it  may  encroach  upon  the  sapwood,  and  after  a  time  reach  the  newer 
sapwood  immediately  under  the  bark,  thereby  causing  the  death  of 
that  portion  of  the  tree,  and,  when  the  entire  diameter  of  the  trunk  i- 
affected,  of  the  whole  tree  itself.  This  is  especially  true  of  the  aspen 
and  the  striped  maple.  As  this  fungus  occurs  so  generally  upon  living 
trees,  it  has  been  thought  that  it  would  cease  growing  after  the  host 
tree  had  died.  From  a  large  number  of  observations  made  by  the 
junior  writer  it  has  been  found  that  this  is  not  really  the  case,  for 
many  trees  have  been  found  entirely  dead  amk  leafless  upon  which 
the  fungus  was  still  growing  vigorously.  This  is  true  not  only, with 
one  or  two  of  the  host  species,  but,  so  far  as  could  he  determined, 
with  all  of  them.  In  some  cases  a  vigorously  growing  new  layer  was 
found  on  the  underside  of  sporophores  growing  on  trees  and  stubs 
which  certainly  must  have  been  dead  for  a  year  or  more.  Standing 
stumps  were  also  found  bearing  living  sporophores  several  years  after 
the  death  of  the  diseased  tree.  This  finding  that  the  sporophores 
will  continue  to  develop  on  dead  wood  is  believed  to  be  of  consider- 
able importance,  because  the  dead  wood  coming  from  a  tree  diseased 
by  this  fungus  in  which  the  mycelium  is  present  must  be  considered 
a  possible  source  for  further  infection  of  healthy  trees. 

INFLUENCE   OF   ENVIRONMENT  ON   PREVALENCE   OF   WHITE    HEART-ROT. 

The  possible  factors  which  may  influence  the  distribution  and 
growth  of  Fomes  igniarius  are  many  and  varied  in  character.  Among 
them  the  following  deserve  consideration:  Climate,  surrounding  for- 
ests, character  of  the  soil,  species  of  host,  age  of  host,  rapidity  of 
growth  of  host,  rate  of  healing  of  branch  wrounds,  and  presence  of 
wounds  on  host. 

The  climate  has  very  little  to  do  with  the  distribution  ami  viru- 
lence of  this  disease.  It  occurs  in  the  humid  forests  of  the  eastern 
United  States  as  well  as  in  the  very  dry  regions  of  New  Mexico  and 
Colorado;  and  it  seems  to  flourish  as  well  in  semitropical  and  tropical 
countries  as  in  the  colder  regions  of  the  north. 

The  character  of  the  surrounding  forest  seems  to  have  absolutely 
no  influence  upon  the  frequency  of  the  disease,  except  as  it  does  or 
does  not  contain  some  of  the  host  species  in  abundance.  The  fungus 
seems  to  occur  with  equal  frequency  in  pure  stands  and  in  mixed 
forests.  In  other  words,  the  aspen  is  found  diseased  just  as  fre- 
quently in  a  mixed  stand  with  other  trees  as  in  a  pure  stand  of 
aspen. 

The  character  of  the  soil  has  little  or  nothing  to  do  with  the  occur- 
rence of  Fomes  igniarius.     The  species  of  the  host,  on  the  other  hand, 
has  a  very  considerable  influence  on  the  frequency  of  the  occuro 
79152— Bui.  149—09 3 


32 


DISEASES   OF    DECIDUOUS   FOREST    TREES. 


of  the  disease.  As  stated  before,  the  aspen,  the  beech,  and  the  but- 
ternut, in  the  order  given,  seem  to  be  the  most  frequently  diseased  of 
all  the  hosts  upon  which  the  fungus  has  been  found. 

The  age  of  the  host  tree  is  probably  the  most  important  factor 
connected  with  the  distribution  of  the  disease.  It  has  been  indi- 
cated that  the  principal  mode  of  entrance  of  the  fungus  is  through 
dead  branches.  Trees  which  are  not  old  enough  to  have  many  dead 
branches  or  which  are  not  old  enough  to  shed  their  lower  branches 

are  free  from  the 
disease.     When 
a  branch  dies  and 
is    broken    off    its 
wood    is    left    ex- 
posed   to    the    at- 
tacks of  the  fungus. 
Where  trees  are 
very     much     sup- 
pressed the  fungus 
may  be  found   on 
trees  only   1   or   2 
inches  in  diameter ; 
but  it  will  be  found 
on  examination 
that   such   sup- 
pressed trees  are  in 
reality  of  a  consid- 
erable age.   In  gen- 
eral it  may  be  said 
that   none   of    the 
common  deciduous 
forest  trees  are  af- 
fected    with     the 
white  heart-rot  be- 
fore   they   are    20 
years  of  age,   and 
most  of  them  will 
not  become  affected  until  they  are  considerably  more  than  20  years 
old.     The  aspen  and  the   butternut  become  infected  after  they  are 
20  to  25  years  of  age.     This  is  especially  true  of  the  aspen,  on  which 
dead  branches  remain  on  the  lower  part  of  the  tree  trunk  for  years 
after  they  are  dead  (fig.  4).     A  clean-stemmed  forest  of  beech  stand- 
ards will  show  far  less  susceptibility  when  50  to  60  years  old  than 
a  similar  stand  in  which  the  dead  branches  stick  out  in  large  num- 
bers from  the  lower  portions  of  the  trunk. 

149 


Fig 


4.— An  aspen  tree  with  many  dead  lateral  branches;  each  of  these 
offers  a  good  entrance  for  wound  fungi. 


DISEASES    CAUSED    BY    WOUND    FUNGI.  33 

The  chances  for  the  healing  of  branch  wounds  arc  generally  very 
much  better  for  a  tree  with  thick  sapwood  than  for  one  with  thin 
sapwood.  From  an  examination  of  trees  affected  with  the  white 
heart-rot  the  following  average  ages  have  been  determined  as  indi- 
cating the  periods  beyond  which  infection  is  liable  to  result  :  Butter- 
nut, about  15  to  20  years;  black  walnut,  about  20  years;  aspen,  20 
to  25  years;  yellow  birch,  20  to  25  years;  beech,  25  to  35  years; 
silver  maple,  about  35  years. 

The  rate  of  growth  of  the  host  tree  affects  chances  \'m  infection 
only  so  far  as  it  influences  the  rate  with  which  such  trees  arc  able  to 
heal  wounds.  Vigorously  growing  trees  of  a  certain  species  will  as  8 
rule  show  less  tendency  toward  infection  than  slow-growing  trei 
the  same  species.  Anything  which  tends  toward  the  healing  of  the 
wounds  formed  in  a  tree  as  it  grows  older  will  reduce  its  chance-  of 
becoming  diseased. 

The  formation  on  trees  of  wounds  other  than  those  caused  by  the 
natural  dying  and  breaking  away  of  branches  on  the  lower  part  of 
the  trunk  has  a  material  influence  on  the  chances  for  infection. 
Short-lived  trees,  like  the  aspen,  in  which  with  increasing  age  there 
is  a  rapidly  increasing  tendency  for  all  branches  to  be  broken  off  by 
windstorms,  show  a  greater  tendency  toward  diseased  conditions  as 
the  trees  reach  maturity  and  afterwards  than  is  the  case  with  trees 
such  as  the  beech  and  oak,  which  are  long  lived,  where  the  tendency 
toward  the  breaking  of  the  branches,  due  to  ice  storms  and  wind- 
storms, is  smaller. 

Summing  up  the  factors  which  control  the  entrance  of  the  false- 
tinder  fungus,  one  finds  that  the  chief  factors,  given  in  the  order  of 
their  importance,  are:  First,  presence  of  wounds  on  the  tree,  this 
involving  the  natural  rate  of  healing  of  lateral  branches,  especially 
on  the  lower  parts  of  the  trunk;  second,  age  of  the  tree;  and  third, 
greater  or  less  tendency  on  the  part  of  trees  to  maintain  a  close  crown, 
reducing  the  chances  for  the  breaking  off  of  large  branches  by  wind- 
storms and  ice  storms. 

ULTIMATE    FATE    OF   DISEASED   TREES. 

A  tree  affected  with  the  white  heart-rot  may  continue  to  live  for 
many  years,  even  if  badly  diseased.  This  is  particularly  true  <>|*  long- 
lived  trees,  like  the  white  oak  and  the  beech,  and  especially  it'  the 
amount  of  wood  destroyed  in  the  trunk  is  so  small  as  to  reduce  the 
strength  of  the  trunk  but  slightly.  Where  the  disease  encroaches 
upon  the  sapwood,  as  in  the  case  of  the  aspen,  trees  may  be  killed 
by  the  disease;  and  this  actually  does  take  place  in  many  instant 
The  chief  destructive  results,  however,  should  be  considered  from 
point  of  view  of  the  wood  destroyed  by  this  fungus. 

149 


34  DISEASES   OF    DECIDUOUS   FOREST    TREES. 

Trees  are  chiefly  grown  for  the  wood  which  they  may  produce,  and, 
with  the  possible  exception  of  shade  trees,  anything  which  destroys 
the  heartwood  of  the  tree  causes  serious  loss.  These  losses  increase 
with  the  age  of  the  tree,  for  the  older  the  tree  becomes  the  more  wood 
is  destroyed.  Ultimately  all  affected  trees  are  blown  over,  it  being 
only  a  question  of  time  before  this  happens.  Fomes  igniarius,  in  fact, 
may  be  considered  one  of  the  chief  factors  determining  the  length  of 
life  of  many  of  the  deciduous  forest  trees. 

EFFECT    OF   THE    FUNGUS    ON    THE    WOOD    STRUCTURE. 

The  diseased  wood  is  very  sharply  bounded  from  the  healthy  wood 
by  black  layers  about  one-eighth  to  one-sixteenth  of  an  inch  in  width. 
(PL  II.)  There  may  be  but  a  single  one  or  there  may  be  several 
arranged  more  or  less  concentrically.  (PI.  II,  fig.  2.)  Just  outside 
of  these  layers  there  is  a  layer  consisting  of  from  three  to  six  annual 
rings,  which  is  darker  in  color  than  the  normal  wood  because  of  the 
infiltration  into  the  same  of  products  of  the  decomposed  wood.  When 
there  is  but  a  single  black  layer  the  rotted  wood  extends  out  to  this ; 
when  there  are  several  such  layers  the  completely  rotted  wood  may 
extend  out  only  to  the  inner  layer,  while  between  the  series  of  layers 
the  wood  will  be  found  in  various  stages  of  partial  decomposition. 
These  black  layers  never  exactly  follow  the  annual  rings  of  growth. 
They  are  usually  very  irregular,  crossing  the  rings  back  and  forth. 
The  completely  rotted  wood  is  white  to  light  yellowish  in  color,  accord- 
ing to  the  species  of  tree  in  which  the  fungus  is  growing.  When 
rubbed  between  the  fingers  it  breaks  up  into  fine  flakes,  but  does  not 
powder.     It  has  lost  its  strength  and  can  no  longer  be  called  wood. 

In  the  completely  decayed  wood  the  mycelium  of  the  fungus  is 
abundant  in  the  large  vessels  and  medullary  rays.  The  walls  of  the 
wood  cells  are  very  much  thinner  than  in  the  normal  cells,  and  in  many 
places  the  middle  lamellae  are  wholly  lacking.  The  addition  of  chlori- 
odid  of  zinc  shows  that  the  walls  which  are  thinnest  are  composed  of 
cellulose.  In  other  words,  one  of  the  principal  effects  of  the  fungus  is 
the  solution  of  the  lignin  elements  of  the  cell  wall.  Extending  from 
the  large  vessels  the  fungous  hyphse  pass  freely  across  the  wood  cells 
and  between  the  remnants  of  the  walls,  binding  them  together  in  a 
more  or  less  compact  mass.  In  the  earlier  stages  of  the  disease  the 
hyphae  develop  most  abundantly  in  the  medullary  rays,  and  from  these 
they  pass  to  the  wood  cells  through  the  pits.  As  a  rule  the  hyphae 
do  not  enter  the  cells  at  other  points  by  a  direct  solution  of  the  walls. 

Shortly  after  a  hypha  has  passed  through  a  pit  the  latter  enlarges, 
forming  an  irregular  hole  in  the  walls,  and  as  the  solution  of  the  walls 
continues  two  or  more  such  holes  coalesce,  forming  a  large  opening. 
At  this  stage  the  affected  cell  walls  still  retain  enough  of  their  lignin 

140 


DISEASES    CAUSED    BY    WOUND    FUNGI. 

elements  to  give  the  lignin  reactions.  The  solution  of  the  middle 
lamella  generally  begins  near  the  enlarged  pit  openings  and  continues 
rapidly  until  the  individual  fibers  fall  apart.  In  the  earlier  stages  of 
the  disease  a  yellowish  substance  which  is  readily  soluble  in  alkalis  is 
present  in  many  of  the  cells.  It  is  this  yellow  color  which  frequently 
passes  outward  in  advance  of  the  actual  destruction  of  the  wood  and 
gives  it  a  darker  coloration.  In  the  earlier  stages  of  decay  t  he  poung 
mycelium  is  colorless,  but  when  exposed  to  the  air  turns  brown. 

PREVENTIVE    MEASU'RES. 

Since  Fomes  igniarius  is  a  wound  parasite,  but  two  methods  of  pre- 
vention can  be  suggested:  One  of  these  consists  in  the  prevention  of 
wounds  and  the  other  in  the  removal  of  the  primary  sources  of  infec- 
tion. On  large  forest  tracts  it  is  at  present  impossible  to  deal  with 
individual  trees  for  the  purpose  of  treating  wounds.  Much  can,  how- 
ever, be  done  in  a  general  way  to  reduce  the  chances  of  natural  wound 
infection.  Attention  has  already  been  called  to  the  fad  thai  the 
tendency  toward  natural  pruning  in  several  species  of  deciduous 
forest  trees,  with  a  consequent  rapid  healing  of  the  wounds  caused  l>\ 
the  breaking  away  of  branches,  very  materially  reduces  the  chances 
for  infection  during  the  early  life  history  of  the  tree,  the  period  during 
which  the  greatest  wood  development  takes  place.  The  growing  of 
straight,  clean-stemmed  trees  results  in  a  healthier  stand,  in  which 
the  chances  for  infection  are  very  much  less  than  in  a  similar  stand  of 
the  same  age  where  the  lower  branches  are  left  dead  on  the  trees  for 
many  years.  It  is  often  practicable  to  assist  the  natural  pruning 
tendencies  of  trees,  and  where  this  is  possible  the  results  will  be  corre- 
spondingly great. 

The  most  practical  method  for  combating  the  heart -rot  of  decidu- 
ous forest  trees  at  the  present  time  is  undoubtedly  the  removal 
of  the  possible  sources  of  infection.  This  is  especially  true  of  more 
or  less  circumscribed  areas.  Wherever  the  management  of  forest 
tracts  is  undertaken,  one  of  the  first  things  which  should  be  done  is 
to  make  a  careful  search  for  trees  already  infected  and  to  promptly 
remove  them. 

Where  an  infected  tree  is  found  it  should  always  be  cut  down. 
Removing  the  sporophores  from  such  trees  and  leaving  the  trees 
standing  is  inadvisable,  because  when  a  fruiting  body  is  removed  it 
will  soon  be  renewed,  thus  necessitating  going  over  tin4  same  tract 
many  times,  with  lessened  chances  for  success.  The  removal  <>f  a 
diseased  tree  is  furthermore  made  advisable  by  the  fact  that  when 
the  sporophores  once  appear  upon  such  a  tree  it  is  <\  sure  sign  that 
the  heartwood  of  that  tree  is  rapidly  being  destroyed.  Where  dis- 
eased trees  are  cut  in  the  earlv  stages  of  infection,  as  evidenced  by 


149 


36  DISEASES   OF    DECIDUOUS   FOREST    TREES. 

the  appearance  of  but  one  or  two  sporophores,  it  may  often  be  pos- 
sible to  save  a  considerable  amount  of  wood  and  lumber.  If  only 
the  sporophores  are  removed  and  the  trees  left  standing,  the  fungus 
continues  growing  in  the  tree,  and  every  year  that  such  a  tree  is  left 
in  the  forest  it  depreciates  in  value,  and  ultimately  becomes  entirely 
worthless.  The  removal  of  diseased  trees  should  be  undertaken  no 
matter  to  what  species  they  may  belong.  So  far  as  we  now  know, 
Fomes  igniarius  when  growing  on  one  host  species  may  infect  the 
others,  and  in  a  deciduous  forest  a  diseased  maple  must  be  consid- 
ered a  source  of  danger  for  the  other  host  species  until  it  is  shown 
that  the  maple  fungus  is  a  distinct  form  which  can  not  infect  other 
species.  In  the  absence  of  such  proof  it  is  advisable  to  cut  down 
the  diseased  maple  and  make  the  protection  of  the  remaining  trees 
certain. 

Any  examination  of  a  forest  tract  for  diseased  trees  should  be 
made  thoroughly,  so  that  all  diseased  trees  may  be  removed,  for  the 
existence  of  a  single  tree  bearing  a  number  of  actively  growing  sporo- 
phores is  sufficient  to  cause  the  infection  of  a  large  area,  since  the 
spores  of  the  false-tinder  fungus  are  very  light  and  are  blown  to 
great  distances  by  the  wind.  All  diseased  wood  should  be  burned, 
as  sporophores  continue  to  develop  on  diseased  wood  even  after 
being  cut  from  the  tree. 

Where  trees  are  sufficiently  valuable  to  warrant  their  being  treated 
individually,  careful  wound  protection  is  advisable.  Wherever  a 
branch  of  any  size  breaks  off  or  where  deep  wounds  are  produced  in 
the  trunks  of  trees,  such  wounds  should  be  carefully  trimmed  so 
that  the  surfaces  are  smooth.  The  wounds  should  then  be  coated 
with  some  good  antiseptic  substance  which  can  be  rapidly  applied 
and  which  will  have  sufficient  penetrating  power  to  infiltrate  for  a 
distance  into  the  wood  fiber.  The  best  material  for  this  purpose  is 
coal-tar  creosote.  This  should  be  heated  until  thoroughly  liquid, 
when  it  can  be  applied  with  a  paint  brush.  It  not  only  has  the 
distinct  advantage  of  killing  all  fungous  spores  which  may  be  pres- 
ent or  which  may  subsequently  lodge  in  the  wound,  but  it  is  also  a 
good  preventive  against  boring  insects. 

The  painting  of  wounds  is  especially  advisable  where  such  wounds 
are  large.  One  instance  which  occurs  to  the  writers  where  such 
wound  treatment  would  have  proved  very  advantageous  if  it  had 
been  carried  out  in  time  was  in  a  large  tract  of  chestnut  forest. 
The  large  trees  had  been  cut  out  a  number  of  years  before  the 
writers'  observations  were  made,  and  shoots  had  started  from  the 
bases  of  the  old  stumps.  These  shoots  were  sufficiently  old  to  have 
formed  heartwood.  A  large  percentage  of  these  young  trees  were 
found  affected  at  the  base  of  their  trunks,  the  fungus  having  entered 

149 


DISEASES    CAUSED    BY    WOUND    FUNGI. 

from  the  old  stump  into  the  heartwood  of  the  living  trees.  U  the 
stumps  had  been  painted  with  creosote  soon  after  the  trees  were 
cut,  this  could  not  have  happened. 

A  similar  instance,  was  noted  some  years  ago  in  a  catalpa  plantar 
tion  in  eastern  Kansas,  where  the  trees  had  been  cul  off  while  they 
were  still  young  in  order  to  stimulate  the  product  ion  of  a  single  large 
shoot.  The  high  percentage  of  diseased  trees  in  this  plantation  is 
directly  ascribed  to  the  fact  that  the  fungus  had  cut  ere.  I  the  new 
shoots  from  the  old  stumps.  It  would  have  been  easy  and  com- 
paratively inexpensive  to  have  coated  the  cut  surfaces  of  the  >t  iimpe 
with  coal-tar  creosote  at  the  time  the  trees  were  cut.  Where  this 
can  be  done,  especially  where  coppice  growth  is  expected,  as  in  the 
case  of  the  chestnut,  such  wound  treatment  may  be  found  practi- 
cable and  will  at  all  times  be  advisable. 

RED    HEART-ROT    CAUSED    BY    POLYPORUS    SULPIII  III.IS. 

The  sulphur  polyporus  (Polyporus  sulphureus  (Bull.)  Fr.)  is  found 
on  a  large  number  of  deciduous  forest  trees,  but  chiefly  on  oaks 
(Quercus  spp.),  chestnut  (Castanea  dentata  (Marsh.)  Borkh.),  maples 
(Acer  spp.),  black  walnut  (Juglans  nigra  L.),  butternut  (Juglans 
cinerea  L.),  alder  (Alnus  sp.),  locust  (Robinia  pseudacacia  L.),  apple 
(Pyrus  malus  L.),  pear  (Pyrus  communis  L.),  etc.  It  is  widely  dis- 
tributed  throughout  the  United  States  and  Canada  and  in  mosl  of 
the  forest  regions  of  Europe,  where  it  is  regarded  as  a  destructive 
parasite,  both  on  deciduous  trees  and  conifers  (32).  Reference  to 
the  disease  caused  by  this  fungus  was  first  made  in  this  country  by 
Galloway  and  Woods  (27),  and  later  by  von  Schrenk  (78). 

The  fruiting  bodies  of  the  sulphur  polyporus  are  among  the  i 
conspicuous  of  the  larger  fungi  found  in  the  forests.     They  form  a 
series  of  shelves,  from  2  to  20  or  more,  overlapping  one  another. 
Sometimes  they  form  very  close  together,  so  as  to  produce  a  large, 
round  mass  about  the  size  of  a  person's  head.     (PL  IV.  fig.  L)     The 
upper  surfaces  at  first  are  a  bright  orange-red,  with  a  brighter  red 
at  the  rims.     As  they  grow  older  they  assume  a  distinct  sulphur- 
yellow  color,  which  is  also  the  color  of  the  under  surface.     When 
young,  the  upper  surface  is  very  moist,  somewhat  hard,  and  when 
bruised  turns  brown.     The  whole  fungus  is  soft  and  fleshy  when 
young,  and  when  squeezed  a  clear  yellowish  liquid  exudes.     As  the 
plant  grows  older  it  becomes  much  harder,  and  short  ly  after  maturity 
becomes  quite  firm  and  brittle.     The  fruiting  bodies  of  this  fir 
very  rarely  remain  on  the  tree  for  any  length  of  time,  b< 
are  attacked  soon  after  reaching  maturity  by  a  number  of  i 
which  speedily  destroy  them.     The  fungus  is  also  eagerly 
mushroom  hunters  on  account  of  its  excellent  and  well-known  edible 
qualities. 

149 


38  DISEASES   OF    DECIDUOUS   FOREST   TREES. 

The  fruiting  bodies  of  Polyporus  sulphureus  usually  occur  in  some 
large  knot  hole  on  the  side  of  the  tree  trunk;  they  are,  however, 
frequently  found  on  stumps  and  fallen  branches.  The  mycelium  of 
the  fungus  is  capable  of  living  in  the  dead  wood  of  a  tree  for  many 
years,  and  when  the  proper  conditions  recur  the  fruiting  bodies  con- 
tinue to  form  each  year,  or  with  a  marked  periodicity  in  alternate 
years.  A  large  branch  was  broken  from  a  chestnut  tree  which  had 
been  diseased  by  the  sulphur  polyporus  for  many  years,  and  accu- 
rate observations  were  made  upon  this  branch  for  five  years.  It 
was  found  that  in  July  or  August  large  masses  of  the  fruiting  bodies 
developed  from  this  branch.  The  fruiting  bodies  of  the  sulphur 
polyporus  form  on  trees  and  stumps  during  the  middle  or  latter  part 
of  the  summer  and,  as  stated,  can  be  found  for  only  a  short  time. 

The  destruction  which  Polyporus  sulphureus  brings  about  in  the 
heartwood  of  trees  is  very  similar  for  all  of  the  host  trees  upon  which 
it  grows,  irrespective  of  whether  they  are  coniferous  or  deciduous 
species.  The  decayed  wood  resembles  a  mass  of  red-browTn  charcoal. 
There  are  various  degrees  of  coloration,  depending  upon  the  host, 
being  darker  in  most  of  the  species  of  oak  and  lighter  in  chestnut 
and  walnut.  The  decayed  wood  is  characterized  by  a  series  of  con- 
centric and  radial  cracks  extending  irregularly  through  it.  (PI.  IV, 
fig.  2.)  These  cracks  develop  as  the  wood  is  destroyed,  and  are 
caused  by  the  decrease  in  volume  of  the  affected  wood.  The  fungus 
forms  thin,  leathery  sheets  in  the  cracks.  In  wood  which  is  badly 
decayed  a  blow  with  a  hammer  will  cause  the  decayed  wood  to  drop 
out  in  the  form  of  fine  powder,  leaving  the  thin  sheets,  consisting  of 
densely  interwoven  threads  of  the  fungus,  as  a  skeleton  framework. 
The  decay  of  the  wood  itself  is  a  very  uniform  one;  in  other  words, 
there  is  no  localized  decay,  but  the  wood  is  uniformly  converted  into 
a  brown,  brittle  substance  which  readily  crumbles  into  a  fine  powder 
when  rubbed  between  the  fingers.  The  red-brown  coloration,  the 
presence  of  large  white  sheets  extending  throughout  the  mass  of  the 
decayed  wood,  and  the  presence  of  numerous  large  and  small  eracks 
extending  radially,  tangentially,  and  transversely  through  the  mass 
of  decayed  wood  readily  enable  one  to  recognize  wood  destroyed  by 
the  sulphur  polyporus.  In  the  oaks  the  broad  medullary  rays  persist 
longest. 

The  age  at  which  trees  are  attacked  by  this  fungus  varies  consid- 
erably with  the  region  in  which  they  are  growing  and  the  conditions 
under  which  they  are  situated.  Healthy,  rapidly  growing  trees  which 
heal  their  wounds  quickly  remain  free  from  the  disease  much  longer 
than  stunted,  poorly  grown  trees.  The  youngest  trees  in  which  the 
red  heart-rot  was  found  were  about  50  years  old. 

Preventive  measures  consist  of  essentially  the  same  treatment  as 
is  suggested  for  Fomes  igniarius.     In  view  of  the  fact  that  the  myce- 

141) 


DISEASES    CAUSED    BY    WOUND    FUNGI.  39 

Hum  of  the  sulphur  polyporus  usually  outers  the  trees  in  the  crown, 
it  is  hardly  practicable  to  attempt  wound  treatment.  The  chief 
endeavor,  therefore,  must  be  concentrated  on  the  removal  of  the 
diseased  trees.  Any  tree  which  shows  signs  of  development  of  sporo- 
phores  of  Polyporus  sulphur eus  should  be  cut  down  at  once,  and  all 
of  the  wood  affected  with  the  mycelium  of  this  fungus  should  be 
burned. 

PIPED-ROT    OF    OAK    AND    CHESTN1  T. 

The  disease  which  we  distinguish  under  the^  name  "piped-rot" 
especially  affects  oak  trees,  particularly  those  of  the  black  oak  group. 
(PL  V,  fig.  1.)  It  has  also  been  found  in  the  beech  {Fagus  atro- 
punicea  (Marsh.)  Sudworth)  and  yellow  birch  (JBetulalutea  Mi<  li\.  1".  . 
This  disease  has  been  found  widely  distributed  throughout  1  he  decid- 
uous forests  of  the  Mississippi  Valley. 

A  similar  disease,  which  is  probably  caused  by  the  same  fungus, 
occurs  in  the  chestnut  (Castanea  dentata  (Marsh.)  Borkh.).  (PL  Y, 
fig.  2.)  The  heartwood  of  affected  trees  has  a  mottled  appearance. 
showing  irregular,  small,  pocket-like  patches  of  white  fibers,  sepa- 
rated by  wood  fibers  still  retaining  almost  the  normal  color  of  the 
heartwood.  The  white  areas  first  appear  in  the  wood  in  the  Form  of 
small  lens-shaped  areas,  which  gradually  increase  in  size  longitudi- 
nally, and  after  a  while  become  confluent,  so  that  in  the  course  of 
time  the  wood  frequently  shows  a  series  of  irregular  white  lines 
extending  longitudinally.  As  the  disease  progresses  the  while  areas 
change  into  small  pockets,  or  holes,  lined  with  fibers.  Where  these 
holes  reach  any  size,  they  frequently  become  filled  with  a  dark,  red- 
brown  mycelium.  In  its  last  stages  the  diseased  wood  is  composed 
of  loose  masses  of  white  fibers  mixed  with  the  brown  mycelium  and 
inclosed  by  thin  unaffected  layers  of  wood.  The  preliminary  sti 
of  the  disease  are  characterized  by  a  darker  coloration  of  the  heart- 
wood,  which  starts  near  the  center  of  the  trunk,  gradually  spreading 
outward  until  it  reaches  the  sapwTood.  In  Plate  V,  figure  1.  this 
darker  coloration  shows  on  the  boundary  between  the  partially 
decayed  wood  and  the  sapwood. 

It  will  be  noted  that  the  disease  is  confined  strictly  t<>  the  heart- 
wood  of  the  tree.  The  changes  just  described  originate  near  some 
branch  stub,  very  much  as  has  been  described  for  Fomes  igniari 
Without  referring  in  detail  to  the  microscopical  changes  which  take 
place  in  the  wood,  it  may  be  said  that  the  white  area-  are  due  i«.  a 
lining  of  cellulose  fibers,  which  stand  out  more  or  less  separately 
from  one  another,  on  the  inner  surfaces  of  the  <a\  iti< 

The  piped-rot  is  one  which  is  readily  distinguished  from  ah  otl 
diseases  of  deciduous  trees  on  account  of  the  speckled  character  of 

149 


40  DISEASES    OF    DECIDUOUS   FOREST    TREES. 

the  affected  wood,  and  it  differs  very  materially  from  a  somewhat 
similar  disease  caused  by  Stereum  frustulosum,  described  later  on,  by 
the  fact  that  the  white  areas  in  the  present  disease  are  not  sharply 
defined,  but  appear  as  more  or  less  regular  white  lines  in  the  mass  of 
the  wood. 

A  disease  very  similar  to  the  one  just  described  for  oaks  has  repeat- 
edly been  found  by  the  senior  writer  in  young  chestnut  trees,  par- 
ticularly in  New  York  and  New  Jersey.  (PL  V,  fig.  2.)  In  both  the 
chestnut  and  the  oak  the  disease  first  manifests  itself  in  the  center 
of  the  tree,  extending  outward  until  it  reaches  the  sapwood.  The 
white  masses,  consisting  of  cellulose  fibers,  are  at  first  confined 
entirely  to  the  spring  wood  of  each  annual  ring.  As  the  disease 
progresses  the  changes  brought  about  by  the  fungus  spread  into  the 
summer  wood  of  each  annual  ring,  and  in  advanced  stages  the  entire 
mass  of  wood  fibers  is  affected. 

Trees  of  all  ages  having  heartwood  are  affected  with  the  piped-rot. 
A  number  of  instances  were  found  of  young  chestnut  trees  growing 
in  a  vigorous  stand  which  were  badly  diseased  when  but  from  25  to 
30  years  old.  In  the  case  of  the  chestnut,  the  disease  frequently 
starts  near  the  ground  line,  extending  up  into  the  trunk.  This  is 
probably  due  to  the  fact  that  the  fungus  causing  the  disease  obtains 
entrance  into  the  young  chestnut  through  the  old  stump  from  which 
so  many  young  chestnut  trees  sprout  in  the  form  of  coppice  shoots. 
In  the  oaks  the  disease  is  more  frequently  found  originating  in  the 
top  and  extending  downward  into  the  trunk. 

There  has  been  much  discussion  as  to  what  fungus  is  responsible 
for  the  piped-rot.  In  a  great  majority  of  cases  no  fruiting  body  of 
any  fungus  can  be  found  on  diseased  trees.  In  many  localities  in 
Missouri  and  adjoining  States, where  the  oaks  are  severely  affected, 
one  frequently  finds  as  many  as  50  per  cent  of  the  young  trees  of  the 
second  growth  affected  with  this  disease;  but  in  spite  of  this  fact  not 
-a  single  fruiting  body  of  any  form  has  been  found  on  the  trees. 

The  piped-rot  is  especially  important  in  the  chestnut.  Preventive 
measures  with  the  chestnut  involve  coating  the  stumps  of  old  trees 
with  some  preservative,  such  as  coal-tar  creosote,  so  as  to  prevent  the 
entrance  of  mycelium  into  the  old  stump  and  thence  into  the  }^oung 
trees  growing  from  the  stump.  This  coating  should  be  applied  very 
soon  after  the  tree  is  cut,  because  after  the  fungus  has  once  obtained 
a  foothold  in  the  stump  it  is  almost  impossible  to  get  rid  of  it.  This, 
of  course,  will  hold  only  where  chestnut  regeneration  is  brought  about 
by  coppice  formation.  In  the  case  of  the  oaks  the  preventive  meas- 
ures suggested  for  the  false-tinder  fungus  will  hold  good. 

149 


DISEASES    CAUSED    BY    WOTTNI)    FUNGI. 


11 


SOFT    ROT    OF    OAKS    CAUSED    BY    POLYPOR1  8    OBTUS1    S. 

A  number  of  species  of  the  black  oaks,  notably  Qut  reus  mafUandica 
Muench.  smdQ.  velutinaljSim.,  are  affected  with  a  disease  of  the  heart- 
wood  which  has  been  determined  by  Spaulding  (94)  to  be  due  to  Poly- 

porus  obtusus  Berk.  Diseased  trees  have  been  found  in  the  eastern 
part  of  the  United  States,  and  notably  in  the  centra]  Mississippi  Val- 
ley; a  large  number  of  trees  are  usually  found  affected  in  a  Locality. 
The  spores  of  the  fungus  germinate  in  the  burrows  of  an  oak-boring 
insect  (Prionoxystus  robiniaeVeck.).  The  fungus  grows  in  1  he  borings 
and  follows  the  in- 
sect burrow  until  it 
reaches  the  heartwood 
of  the  tree;  it  then 
spreads  out  from  this 
point,  both  up  and 
down  the  trunk,  and 
gradually  brings 
about  a  form  of  soft 
rot.  (Fig.  5.)  The  dis- 
eased wood  is  lighter 
in  color  than  the 
heartwood  of  the 
healthy  tree,  and  in 
its  last  stages  turns 
almost  white.  "The 
diseased  wood  retains 
its  fibrous  appearance, 
but  breaks  much  eas- 
ier than  does  the 
healthy  wood.  It 
does    not     have     the 

Shrinkage     cracks      Fig.  5.— A  living  black  oak  i  re- wiiii  a  sporophoreo 
which  are   SO    cliarac-  obtusus  growing  out  of  the  opening  of  an  insect  burrow. 

teristic  of  some  of  the  wood  rots;  neither  docs  the  affected  tissue 
crumble  between  the  fingers  nor  break  very  easily  into  small  flakes' 
(94).  The  fungus  grows  in  the  trees  rapidly,  extending  up  and  down 
in  the  heartwood  and  growing  outward  until  it  reaches  the  sapwood. 
Affected  trees  are- weakened  to  such  an  extent  within  one  or  two  years 
after  their  first  attack  that  the  slightest  windstorm  causes  the  trunks 
to  break. 

The  sporophore  of  Poh/porus  obtusus  is  a  very  characteristic  one. 
It  usually  appears  at  the  original  insect  burrow,  where  it    forms 
thick,  more  or  less  hoof  shaped  shelf;  in  some  cases  tv 
shelves  may  form,  one  immediately  above  the  other.     The  spo 

149 


42  DISEASES   OF    DECIDUOUS   FOREST    TREES. 

phores  are  almost  perfectly  white  when  they  first  form,  but  gradually 
turn  darker,  and  in  old  age  are  light  brown.  The  upper  surface  is 
very  soft  and  hirsute,  and  near  the  point  of  insertion  is  much  cracked, 
having  the  appearance  of  weathered  corn  pith.  One  of  the  most 
striking  features  of  the  sporophore  is  the  manner  in  which  the  rough, 
hairy  upper  surface  extends  over  the  rounded  edge  on  to  the  lower 
side  of  the  sporophore  for  one-eighth  to  one-fourth  inch  or  more ;  the 
lower  surface  is  the  same  color  as  the  top.  The  pores  are  very  irregu- 
lar in  shape,  with  uneven  and  jagged  edges,  giving  the  whole  lower 
surface  a  somewhat  spiny  appearance.  The  sporophore  never  attains 
any  great  age,  because  it  is  attacked  with  great  avidity  by  various 
insects  which  destroy  it  rapidly. 

HEART-ROT    CAUSED    BY    FOMES    NIGRICANS. 

A  brown  heart-rot  of  deciduous  trees,  especially  of  the  yellow  birch 
(Betula  lutea  Michx.  f.),  willow  (Salix  sp.),  and  aspen  (Populus  tremu- 
loides  Michx.),  is  due  to  Fomes  nigricans  Fr.  This  fungus  is  found 
frequently  in  the  Northern  States  from  Maine  to  Oregon  and  occurs 
most  often  on  the  yellow  birch.  Its  method  of  attacking  trees,  its 
rate  of  development,  and  its  spread  from  tree  to  tree  are  very  much  the 
same  as  those  described  for  Fomes  igniarius. 

The  fungus  is  a  parasite  in  the  sense  that  it  attacks  the  heartwood 
of  the  tree,  gaining  entrance  through  some  wound.  The  decayed 
heartwood  is  reddish  brown  in  color,  very  soft,  and  has  very  much  the 
uppearance  of  wood  destroyed  by  Fomes  igniarius.  Lindroth  (48) 
in  a  recent  description  of  the  changes  which  this  fungus  brings  about 
in  birch  wood  notes  a  number  of  distinct  regions  of  destruction.  In 
the  trees  examined  by  the  writers  they  have  not  been  able  to  differ- 
entiate such  distinct  zones.  Plate  VI,  figure  1,  shows  a  cross  section 
of  a  thrifty  birch  tree,  in  which  it  will  be  noted  that  the  destruction 
is  more  or  less  uniform,  beginning  at  the  center  of  the  trunk  and  ex- 
tending outward  almost  to  the  bark.  The  decayed  wood  is  spongy 
and  will  not  powder  when  rubbed  between  the  fingers. 

The  most  striking  feature  in  connection  with  this  type  of  heart-rot 
is  the  extent  to  which  the  decay  involves  the  whole  trunk.  It  starts 
at  the  center  and  progresses  outward,  gradually  involves  the  sapwood, 
and  ultimately  reaches  the  bark,  killing  the  tree.  A  similar  progress 
of  decay  involving  the  sapwood  has  already  been  noted  for  Fomes 
igniarius.  This  type  of  disease  is  very  striking  in  such  trees  as  the 
paper  birch  (Betula  papyrifera  Marsh.).  The  minute  changes  which 
take  place  in  wood  destroyed  by  Fomes  nigricans  are  of  less  interest 
in  this  connection;  they  have  been  fully  studied  and  described  by 
Lindroth  in  the  article  already  mentioned  (48). 

149 


DISEASES    CAUSED    BY    WOUND    FUNGI.  };; 

The  fruiting  bodies  of  Fomes  nigricans  appear  on  diseased  tr< 
single,  large,  more  or  less  hoof  shaped  bodies;  there  may  be  bul  one 
of  these  on  a  tree,  or  up  to  six  or  eight,  but  in  no  case  is  more  than 
one  fruiting  body  found  at  one  point.  The  sporophores  are  large, 
woody  structures,  resembling  those  of  Fomes  igniarius.  It  has  been 
held  by  Murrill  (58)  that  Fomes  nigricans  is  but  a  form  of  Fomes 
igniarius. 

The  top  of  the  sporophore  shows  a  number  of  concentric  ridges  in 
which  large  numbers  of  sharply  defined  shallow  assures  appear  as  the 
sporophore  grows  older.  These  fissures  extend  radially  and  trans- 
versely across  the  top  and  give  the  appearance  of  numerous. black 
lines.  The  top  as  a  whole  is  smooth,  differing  in  this  respect  from 
many  types  of  Fomes  igniarius,  in  the  older  forms  of  \\  bich  the  top  is 
very  rough;  the  older  portions  of  the  surface  are  jet  black.  Thia  is 
likewise  usually  true  of  the  younger  layers,  although  we  have  noted 
instances  where  the  most  recently  formed  outer  edge  is  dark  brown 
in  color.  One  of  the  most  characteristic  properties  of  the  top  of  the 
sporophore  is  its  intense  hardness.  When  cut  into,  this  hard  layer, 
which  is  usually  about  one-sixteenth  of  an  inch  in  thickness,  has  a  very 
characteristic  horny  texture.  The  lower  surface  of  the  sporophore  is 
rounded,  and  usually  dark  brown  in  color;  the  pores  are  very  minute 
and  regular.  The  substance  of  the  sporophore  is  tough  and  almost 
woody.  The  sporophores  are  of  all  sizes,  varying  from  an  inch  to  10 
or  12  inches  in  width.  As  a  rule,  when  perfect  they  are  characterized 
by  great  regularity  in  their  proportions,  and  when  once  recognized, 
one  can  hardly  fail  to  distinguish  this  species. 

Fomes  nigricans  sometimes  forms  very  curious  fruiting  bodies  on 
birches,  the  cause  for  which  has  not  yet  been  definitely  determined. 
For  many  years  observers  and  collectors  in  the  Northern  States  have 
reported  finding  irregular,  black,  jagged  masses,  having  the  appear- 
ance of  dried,  hard  pitch,  growing  out  from  wounds  on  birch  trees 
(PL  VI,  iig.  2).  These  masses  look  like  large  warts.  They  are  jet 
black  in  color,  very  deeply  fissured  and  broken,  and  of  all  conceivable 
shapes.  They  increase  in  size  from  year  to  year  in  a  very  irregular 
way  without  any  signs  of  pore  formation.  The  mass  of  l  \\<^o  bodies 
is  very  hard  and  when  examined  closely  shows  thai  it  is  composed  of 
masses  of  dark  brown  hyphae  the  walls  of  which  have  I ><•<•«. mr  ex< 
sively  thickened,  giving  the  whole  a  woody  texture.  The  writers 
have  observed  these  black  structures  for  a  Dumber  of  years  without 
being  able  to  identify  them;  the  senior  writer  suggested  tentatively, 
some  years  ago,  that  they  might  be  undeveloped  sporophore 
Fomes  igniarius. 

In  his  recent  paper  Lindroth  (48)  describes  similar  bodies  growir 
on  birches  in  Europe,  and  definitely  calls  them  abortive  bodies 


149 


44  DISEASES    OF    DECIDUOUS   FOREST    TREES. 

Fomes  nigricans.  While  there  are  no  signs  of  pores  or  other  struc- 
tures which  would  enable  one  to  definitely  say  that  these  black 
masses  are  undeveloped  sporophores  of  this  fungus,  the  writers  are 
inclined  to  agree  with  Lindroth  that  this  is  the  case.  This  supposition 
is  strengthened  by  the  fact  that  wherever  these  black  masses  occur 
on  birch  trees  the  characteristic  decay  of  the  wood  usually  caused  by 
Fomes  nigricans  will  always  be  found.  Attention  should  be  called  to 
the  very  frequent  appearance  of  these  sterile  masses — a  form  of 
growth,  so  far  as  known  to  the  writers,  which  has  not  been  known  for 
any  other  wood-rotting  fungus. 

DISEASE    CAUSED    BY    HYDNUM    ERINACEUS. 

The  coral  fungus  (Ilydnum  erinaceus  Bull.)  produces  a  white  rot 
of  many  deciduous  species,  chiefly  of  oaks.  It  has  been  found  abun- 
dantly on  both  the  red  oak  (Quercus  rubra  L.)  and  white  oak  (Q.  alba 
L.),  where  its  large  white  fruiting  bodies  form  very  conspicuous 
objects  (PL  VII,  fig.  2). 

The  fungus  enters  the  trees  very  much  as  do  the  other  wood-rotting 
fungi,  growing  from  branch  stubs  into  the  heart  of  the  tree.  It  like- 
wise gets  in  through  the  tunnels  of  the  oak  borer  in  the  same  manner 
as  does  Polyporus  obtusus.  The  diseased  wood  in  its  final  stages  is 
soft  and  mushy,  so  that  when  squeezed  considerable  water  flows  out. 
Trees  in  an  advanced  state  of  decay  have  numerous  large  holes  in  the 
heartwood,  which  are  filled  with  masses  of  light  yellowish,  fluffy 
fungous  mycelium  (PL  VII,  fig.  1).  During  the  early  stages  of  the 
disease  the  heartwood  of  the  oak  turns  lighter  in  color,  and  the  more 
rapid  destruction  of  the  wood  between  the  medullary  rays  is  very 
characteristic  of  this  type  of  disease.  As  the  disease  progresses,  the 
wood  becomes  spongy  and  is  practically  wholly  destroyed,  so  that 
cavities  such  as  have  been  referred  to  form;  indeed,  the  entire  heart 
of  the  tree  may  be  destroyed,  leaving  but  a  hollow  shell  consisting  of 
sapwood. 

The  white  rot  caused  by  the  coral  fungus  can  be  recognized  by  the 
very  wet,  soggy  nature  of  the  diseased  wood.  The  fruiting  bodies  of 
the  coral  fungus  form  on  broken  trunks  and  on  standing  trees,  issuing 
frequently  from  the  holes  of  the  oak  borer.  They  are  snow-white  in 
color,  anywhere  from  1  to  10  or  12  inches  in  diameter,  and  almost 
spherical  in  shape.  They  may  appear  singly  or  in  groups.  The  mass 
of  the  sporophores  is  fleshy,  and  drops  of  glistening  fluid  frequently 
exude  over  the  entire  surface  of  the  top.  The  top  surface  is  more  or 
less  roughly  hairy.  The  bulk  of  the  sporophore  consists  of  an  exceed- 
ingly large  number  of  white  teeth,  or  spines,  bearing  the  spores. 
-  Very  little  is  yet  known  as  to  the  exact  distribution  of  this  fungus 
and  of  the  host  trees  which  it  attacks.     Judging  from  the  number  of 


149 


DISEASES    CAUSED    BY    WOUND    FUNGI.  45 

times  that  the  writers  have  found  it,  particularly  in  the  centra]  United 

States,  it  is  fairly  common  on  both  the  while  oak  and  the  red  oak. 

Trees  50  to  60  years  old  frequently  show  the  soft  heart-rot  without 
any  signs  of  the  sporophores.  The  latter  appear  to  hum  rarely,  and 
after  their  formation  are  very  short  lived,  because  they  are  readily 
attacked  by  insects.  Even  where  the  insects  do  nol  destroy  them, 
they  dry  up  very  soon  after  they  have  reached  maturity,  and  shrivel 
into  insignificant  black  masses,  which  can  be  recognize!  I  with  difficulty. 

BLACK   LOCUST   DISEASE    CAUSED    BY   FOMES    BIMOSUS. 

The  black  locust  (Robinia  pseudacacia)  is  universally  attacked  by 
yellow-rot,  which  completely  destroys  the  heartwood  of  living  i 
A  detailed  description  of  the  changes  which  are  caused  by  this  fungus 
in  the  wood  of  locust  trees  was  published  by  von  Schrenk  (80  .  The 
disease  has  been  found  in  practically  the  entire  area  where  the  black 
locust  grows,  from  Massachusetts  to  New  Mexico.  It  is  especially 
prevalent  in  the  southern  Appalachian  forests  and  in  some  portions 
of  New  Mexico,  where  a  very  large  percentage  of  the  locusl  trees  are 
destroyed. 

Infection  takes  place  through  older  branches  and  through  the  tunnels  made  by  the 
locust  borer  (Cyllene  robiniae) .    Wounds  are  frequent  in  older  trees,  caused  by  the  brit- 
tle nature  of  the  branches  of  the  locust.     The  fresh  wounds  are  favorable  point 
the  germination  of  the  spores,  and  it  is  an  easy  matter  to  find  all  Btagee,  from 
recently  infected  to  trees  where  the  whole  side  of  a  trunk  has  evidently  been  Lnf< 
from  one  branch.     The  changes  which  the  fungus  brings  about   in  the  Locusl  wood 
are  very  striking.     The  hard,  resistant  wood  is  transformed  into  a  eofl    yellow  or 
brown  mass,  which,  when  wet,  is  more  or  less  spongy.     The  almost  flint-like  chars 
of  the  wood  is  wholly  gone  in  completely  decayed  wood,  which  can  In- cut  almost  like 
cheese.     (80.) 

One  of  the  most  characteristic  features  of  the  decayed  wood  is  that 
the  decay  extends  out  from  the  center  of  the  heartwood  in  a  series  of 
radial  lines.  These  radial  lines  are  produced  by  the  fungous  thread- 
growing  outward  through  some  of  the  large  medullary  r.-i  \  s. 

The  sporophores  of  Fomes  rimosus  Berk,  are  large  and  conspicu- 
ous.    The  mature  form  consists  of  one  or  more  broad  shelves,  the  top 
of  which  meets  the  lower  side  at  an  angle  of  from  30  to  35  degn 
They  are  usually  almost  twice  as  wide  laterally   as  from   front    to 
back.     In  the  Southern  States,  and  particularly  in  the  Appalachian 
Mountain  forests,   the  sporophores   have   a   decidedly    hoof-shaped 
character,  almost  as  much  so  as  those  of   Fomes  f omental 
VIII,  fig.  1).     Similar  hoof-shaped  forms  have  been  found  by  Hedg- 
cock  in  New  Mexico.     In  either  form  the  upper  surface   in   older 
specimens  shows  a  number  of  ridges  which  are  \cr\   distinct  in  the 
younger  part  of  the  sporophore,  but  become  almost  obliterated  a 
sporophore  grows  older.     The  youngest  part  of  the  sporophoi 

149 


46  DISEASES    OF    DECIDUOUS   FOREST    TREES. 

a  very  smooth,  rounded  edge,  which  in  most  cases  is  light  brown, 
appearing  as  if  polished,  or  sometimes  somewhat  villous.  The  older 
parts  of  the  upper  surface  are  dark  brown,  almost  black,  and  are 
broken  into  many  small  pieces  by  numerous  fissures.  Many  old 
sporophores  have  a  jagged,  extremely  rough  surface  because  of  these 
fractures.  Lichens  and  moss  frequently  cover  the  older  parts. 
The  lower  side  of  the  sporophore  is  dull  red-brown  and  the  interior 
is  light  brown,  with  evident,  though  imperfect,  indications  of  strati- 
fication. The  pores  are  continuous  through  several  layers,  remaining 
open  for  two  or  three  years. 

The  sporophores  often  develop  from  the  openings  of  tunnels  of 
the  locust  borer  or  from  broken  branch  stubs.  It  is  not  unusual  to 
find  eight  or  ten  sporophores  on  one  diseased  tree. 

Wood  which  is  decayed  by  Fomes  rimosus  when  cut  from  the  tree 
will  remain  unchanged  for  a  great  many  years.  In  other  words,  the 
fungus  will  not  continue  to  form  fruiting  bodies  on  such  decayed 
wood  as  does  the  false-tinder  fungus  previously  mentioned.  The 
only  preventive  measures  which  can  be  taken  are  to  care  for  wounds, 
and  preferably  to  cut  all  locust  trees  before  they  reach  an  age  where 
their  branches  begin  to  break  off  in  large  numbers.  For  most 
localities  this  will  be  from  sixty  to  seventy-five  years. 

WHITE    HEART-ROT    OF   ASH    CAUSED    BY    FOMES    FRAXINOPHILUS. 

A  disease  caused  by  Fomes  fraxinophilus  Peck  upon  white  ash 
(Fraxinus  americana  L.)  in  the  Mississippi  Valley  has  been  described 
in  a  previous  publication  by  von  Schrenk  (84).  It  attacks  white 
ash  trees  of  all  ages,  usually  those,  however,  which  are  more  than  7 
inches  in  diameter.  The  fungus  is  a  distinct  wound  parasite,  the 
parasite  starting  its  development  in  a  branch  stub,  whence  it  grows 
into  the  heartwood  of  the  trunk.  The  diseased  wood  first  of  all 
turns  darker  in  color.  The  next  stage  of  the  disease  is  marked  by  a 
bleaching  of  the  color  in  the  spring  wood  of  the  annual  rings;  these 
gradually  turn  back  to  the  original  straw  color,  and  then  white  in 
spots.  Ultimately  the  whole  tissue  becomes  a  loose,  spongy  mass 
of  wood  fibers.  The  completely  rotted  wood  is  straw  colored,  very 
soft  and  nonresistant,  and  readily  absorbs  water. 

The  sporophores  of  Fomes  fraxinophilus  appear  at  the  base  of 
branch  stubs  or  in  wounds,  either  alone  or  several  together.  The 
mature  sporophore  is  nearly  triangular  in  cross  section;  it  has  a 
broad,  rounded  edge,  which  at  first  is  white  and  gradually  turns 
darker  until  it  becomes  somewhat  straw  colored.  The  older  por- 
tions of  the  upper  surface  are  dark  brown  or  black  and  are  very  hard 
and  woody.  The  younger  part  grows  out  over  the  older  portions, 
which   makes   the  sporophore  look  somewhat  sulcate.     The   main 

149 


DISEASES    CAUSED    BY    WOUND    FUNGI.  47 

body  of  the   mature  sporophore  is  very  hard    and   woody.     It    is 
obscurely  zoned,  pale  brown  and  rust  colored. 

The  white  ash  disease  is  one  that  can  be  combated  with  success 
provided  careful  attention  is  given  to  protecting  wounds.  Vigor- 
ously growing  trees  appear  to  be  particularly  susceptible  to  the 
disease,  since  where  one  diseased  tree  occurs  those  in  the  immediate 
vicinity  are  very  likely  to  become  infected  shortly  after.  The  cut- 
ting out  of  all  trees  which  show  signs  of  sporophore  formation  is 
therefore  recommended. 

RED    HEART-ROT    OF   BIRCH    CAUSED    BY   FOMES    Jll.\i   8. 

A  heart-rot  of  the  river  birch  (Betula  nigra  L.)  has  been  found 
repeatedly  in  Missouri  and  Arkansas.  It  is  caused  by  Fvmes  fvhms 
Fr.,  which  is  apparently  the  fungus  which  causes  such  an  extensive 
destruction  of  the  olive  trees  in  Italy.  It  has  been  reported  in  this 
country  on  a  number  of  hosts,  but  especially  on  the  river  birch. 

The  sporophores  generally  grow  near  a  branch  stub.  They  are 
very  woody  and  hard.  The  young  sporophore  appears  as  a  small 
knob,  which  gradually  increases  in  size  and  when  mature  is  almost 
triangular  in  the  cross  section.  The  upper  surface  is  at  first  rough 
or  hairy,  but  later  becomes  perfectly  smooth  and  almosl  flinty  in 
texture.  A  number  of  very  fine  irregular  fissures  form  on  the  upper 
surface  in  older  sporophores,  extending  parallel  to  the  edge.  The 
upper  surface  never  becomes  deeply  fissured  and  broken,  as  in  Fomes 
igniarius  and  F.  rimosus.  The  upper  surface  when  mature  is  a  dull 
red-brown;  the  lower  surface  is  very  smooth  and  joins  the  upper  at 
an  angle  of  about  30  degrees.  The  pores  are  extremely  minute, 
hardly  visible  to  the  naked  eye.  The  mass  of  the  sporophore  is 
very  hard  and  woody  and  shows  decided  evidence  of  stratification. 
No  detailed  investigations  have  as  yet  been  made  as  to  the  nature 
of  the  decay  induced  by  the  fungus.  Diseased  trees  show  a  brown 
rot  of  the  heartwood  extending  for  some  10  or  12  feet  both  up  and 
down  from  the  points  where  the  sporophores  are  growing.  The 
wood  has  a  red-brown  appearance  and  crumbles  to  pieces  wheE 
crushed.  There  are  no  signs  of  felt-like  sheets  such  as  occur  in 
similar  brown-rotted  wood  when  destroyed  by  the  sulphur  porj  porus 
(Polyporus  sulphureus) . 

SOFT    HEART-ROT    OF    CATALPA    CAUSED   BY   POLTSTICTUS    VERSICOLOR, 

The  hardy  catalpa  (Catalpa  speciosa  Warder)  is  affected  with  but 
one  very  serious  disease,  which  has  been  described  at  length  by  von 
Schrenk  (83).     In  the  early  stages  of  the  disease  the  wood  nea 
center  of  the  tree  becomes  discolored,  and  this  discoloration  gradually 

79152— Bui.  149—09 4 


48  DISEASES   OF    DECIDUOUS   FOREST    TREES. 

spreads  outward.  The  discolored  areas  gradually  disintegrate  until 
the  wood  becomes  straw-yellow.  In  the  final  stages  of  the  disease  the 
entire  heartwood  becomes  converted  into  a  soft  rotted  mass  which 
resembles  pith  in  its  consistency. 

The  catalpa  disease  is  caused  by  Polystictus  versicolor  Fr.  The 
spores  of  this  fungus  germinate  in  some  wound,  or  generally  at  a 
branch  stub.  The  fungus  grows  through  the  stub  and  spreads  up 
and  down  in  the  trunk.  After  a  time  fruiting  bodies  form  on  the 
outside  of  the  trunk,  generally  near  a  branch  wound.  The  sporo- 
phores  are  sessile  and  a  great  many  of  them  grow  together,  one  above 
the  other.  They  are  readily  recognized  by  the  soft,  hairy  upper 
surface,  with  alternate  bands  of  light  and  dark  color.  The  margin 
of  the  sporophore  is  irregularly  wavy  when  dry.  Fresh  sporophores 
are  fleshy,  but  as  they  grow  older  they  become  tough  and  somewhat 
brittle,  and  the  front  edge  curls  in. 

Hardy  catalpa  trees  are  affected  early  in  life.  In  the  instances 
described  the  trees  were  about  18  }Tears  old.  In  order  to  prevent 
the  spread  of  the  disease  most  attention  should  be  paid  to  the  careful 
coating  of  all  wounds  made  in  pruning  or  in  cutting  off  root  suckers. 

HEART-ROT    OF    OAKS    CAUSED    BY    FOMES    EVERHARTII. 

Fomes  everhartii  Ellis  &  Galloway  (16)  has  been  found  repeatedly 
growing  on  blackjack  oak  (Quercus  marilandica  Muench.),  causing  a 
disease  almost  indistinguishable  from  that  described  for  the  false- 
tinder  fungus  {Fomes  igniarius).  Affected  trees  frequently  show  in  a 
very  striking  manner  that  the  mycelium  of  this  fungus  is  capable  of 
growing  into  the  sapwood  of  the  living  tree  (PL  III,  fig.  2) .  In  the 
upper  part  of  the  figure  it  will  be  noted  that  the  fungus  has  destroyed 
not  only  the  heartwood  but  has  extended  through  the  sapwood, 
where  it  has  evidently  been  growing  for  about  three  years,  as  indi- 
cated by  the  callous  formation  on  the  edges  of  the  diseased  part. 

The  sporophores  of  Fomes  everhartii  are  large,  conspicuous  woody 
bodies  which  grow  out  from  wounds.  They  are  generally  broad,  of 
a  dark  rusty  brown  color,  with  a  deeply  cracked  and  fissured  upper 
surface.  The  lower  surface  is  red-brown  in  color,  with  extremely 
minute  round  pores. 

WHITE-ROT    CAUSED    BY   POLYPORUS    SQUAMOSUS. 

Buller  (9)  has  recently  described  a  white-rot  of  deciduous  trees 
caused  by  Poly porus  squamosus  Huds.,  which  occurs  upon  the  maple 
(Acer  pseudoplatanus  L.,  A.  platanoides  L.,  A.  sacclxarinum  L.,  A. 
negundo  L.),  pear  (Pyrus  communis  L.),  oak  (Quercus  sp.),  elm  (  TJlmus 
montana  With.) ,  walnut  (Juglans  regia  L.) ,  linden  (  Tilia  europaea  L.), 

140 


DISEASES    CAUSED    liY     WOUND    FUNGI.  4'J 

willow  (Salix  sp.),  ash  (Fraxinus  excelsior  L.),  birch  {Betula 
horse  chestnut  (Aesculus  Jiippocastanum  L.),  and  beech  (Fagua  %yl- 
vatica  L.).  Buller's  descriptions  refer  especially  to  the  occurrence 
of  this  disease  in  Europe;  and  although  the  writers  have  found  the 
same  but  rarely  in  this  country,  ii  occurs  no^  and  then  in  the  North- 
ern States.  Freeman  (23)  mention,  its  occurrence  in  Minnesota, 
although  he  states  that  it  is  usually  found  on  dead  logs  or  stumps. 
In  view  of  its  widespread  occurrence  in  Europe  on  living  trees  ii  is 
probable  that  it  will  be  found  in  this  country  more  frequently  than 
is  known  at  the  present  time.  4 

According  to  Buller,  diseased  maple  wood  becomes  much  whiter 
than  the  normal  wood.  Irregularly  scattered  series  of  white  lines 
appear  in  the  diseased  wood,  resembling  the  decay  brought  about  l>\ 
Fomes  applanatus  as  described  by  Heald  (38). 

The  fruiting  bodies  are  almost  circular  and  are  attached  to  the 
trunk  of  the  tree  by  a  marked  stipe,  They  grow  to  a  considerable 
size,  individuals  1  foot  in  diameter  not  being  at  all  infrequent,  and 
Buller  mentions  a  sporophore  which  measured  2  feet  2  inches  across. 
He  states  that  they  are  remarkable  for  their  rapid  rate  of  growth. 

The  fruiting  bodies  are  annual  and  are  produced  from  May  until 
September.  They  are  at  first  soft  and  juicy,  but  as  they  grow  older 
and  drier  they  become  very  tough.  The  upper  surface  is  character- 
ized by  the  presence  of  a  series  of  large  scales,  which  give  it  a  rough- 
ened appearance.  Buller  states  that  when  a  tree  has  been  killed  by 
Polyporus  squamosus  the  fungus  can  still  continue  its  annual  produc- 
tion of  fruiting  bodies. 

TWO    SAP-ROTS. 

In  addition  to  the  fungi  which  have  been  previously  described,  there 
are  two  forms  which  are  usually  considered  parasitic  on  deciduous 
forest  trees.  These  are  Fomes  fomentarius  (L.)  Fr.  and  Polyp 
betulinus  (Bull.)  Fr.  Both  of  these  fungi  are  very  common  all  over 
the  Northern  Hemisphere,  and  both  of  them  have  been  described  by 
various  authors  (Tubeuf  (102),  Mayr  (53),  Hartig  (34,  35),  Freeman 
(23),  et  al.)  as  parasitic  on  living  trees.  The  manner  in  which  they 
attack  trees,  however,  is  so  different  from  that  described  for  the  fungi 
which  cause  distinct  heart-rots  of  living  trees  that  they  should  be 
considered  in  a  separate  group. 

In  spite  of  numerous  observations  which  the  writers  have  made 
for  years  upon  these  two  fungi,  they  are  not  prepared  t->  class  them 
with  the  preceding  forms,  nor  can  they  state  definitely  that 
should  be  considered  as  parasitic  on  living  trees.      Distinction  hct  v. 
a  parasitic  fungus  growing  on  a  forest  tree  and  one  growing 
phyte  is  a  difficult  matter.     The  writers  have  attempted  I 

149 


50  DISEASES   OF    DECIDUOUS   FOREST    TREES. 

groups— one  including  those  fungi  which  gain  entrance  through 
wounds  or  branch  stubs  and  grow  in  the  heartwood  of  the  living  trees; 
the  other,  those  fungi  which  grow  on  dead  wood,  including  both  wood 
removed  from  the  living  tree  and  in  some  cases  dead  heartwood  or 
sapwood  actually  exposed  to  the  air,  but  still  forming  a  part  of  the 
living  and  actively  growing  tree.  While  the  first  class  is  not  dis- 
tinctly parasitic  in  the  ordinary  sense  that  a  rust  is  parasitic  on  a  living 
leaf,  the  fungi  are  nevertheless  always  associated  with  living  trees, 
and  their  mode  of  life  may  be  called  parasitic. 

Fomes  fomentarius  and  Polyporus  bctulinus  rarely,  if  ever,  cause  a 
heart-rot;  that  is,  they  rarely  gain  entrance  through  a  branch  stub 
into  the  center  of  the  tree  and  cause  a  type  of  decay  starting  at  the 
center  and  extending  outward.  Both  of  them  are  found  as  frequently 
(and  probably  in  the  greater  number  of  cases)  on  dead  trees  or  logs 
as  they  are  on  living  trees.  The  writers  have  found  both  of  these 
forms  growing  on  living  and  on  dying  trees,  but  they  are  unable  to 
say  whether  these  trees  were  weakened  by  the  fungi  or  whether  the 
fungi  were  able  to  grow  upon  the  trees  because  they  were  already 
weakened  by  other  causes.  The  sporophores  of  both  of  these  fungi 
grow  in  large  numbers  on  standing  dead  trees,  and  they  have 
frequently  been  held  responsible  for  the  death  of  trees.  The  most 
exhaustive  investigation  of  one  of  these  fungi  was  made  by  Mayr  (53), 
who  transplanted  wood  infected  by  the  mycelium  of  Polyporus 
betulinus  into  the  sapwood  of  healthy  trees  and  found  that  in  a- 
period  from  August  to  November  the  mycelium  had  grown  2\ 
centimeters  into  the  sound  wood  around  the  point  of  infection. 
He  regards  this  as  evidence  of  the  parasitic  nature  of  the  fungus, 
but  the  final  results  should  be  known  before  passing  judgment  upon 
his  experiments. 

In  view  of  the  common  occurrence  of  these  fungi,  they  are  de- 
scribed with  the  expectation  that  further  investigation  may  decide 
their  true  nature. 

DECAY   CAUSED    BY   FOMES    FOMENTARIUS. 

Fomes  fomentarius  (L.)  Fr.  occurs  in  the  United  States  mainly 
on  the  beech  (  Fagus  atropunicea  (Marsh.)  Sud  worth)  and  the  yellow 
birch  (Betula  luteaMichx.  f.),  but  it  also  occurs  on  other  deciduous 
species.  The  sporophores  are  distinctly  hoof  shaped.  They  appear 
as  small  rounded  knobs  on  the  surface  of  the  trunk;  that  is,  they 
are  not  confined  to  branch  stubs,  but  occur  also  at  other  wounds. 
Their  upper  surface  is  smooth  and  more  or  less  definitely  marked 
by  concentric  ridges.  The  older  sporophores  are  uniformly  gray 
and  have  a  somewhat  powdered  appearance.  The  lower  surface  is 
red-brown   and  shows   numerous   regular   small   round   pores.     The 

149 


DISEASES    CAUSED    BY    WOUND    FUNGI.  f,  ] 

margin  of  the  newer  layer  is  grayish  white  and  very  soft  and  velvety. 

The  sporophores  usually  occur  singly,  although  two  or  mow  may 
grow  into  an  irregular  mass  where  they  grow  oul  from  the  trunk 
in  close  proximity  to  one  another.  A  diseased  trunk  bears  From 
one  to  twenty  or  more  of  the  sporophores  scattered  over  the  surface. 
The  decay  induced  by  Fomes  fomentarius  starts  in  the  outer  Bap- 
wood  immediately  under  the  bark,  and  proceeds  inward  until  ii 
reaches  the  center  of  the  tree.  (PL  VIII,  fig.  2.)  The  decayed  wood 
is  characterized  by  numerous  irregular  black  lines,  bounding  areas 
of  wood  not  yet  completely  decayed.  Wholly  dotted  wbod  is  very 
soft  and  spongy,  light  yellowish  in  color,  and  crumbles  between 
the  fingers  into  numerous  separate  wood  fibers. 

Beech  and  birch  trees  are  usually  decayed  in  the  tops,  and  the 
fungus  gradually  spreads  down  toward  the  base  of  the  trunk.  It  is 
no  unusual  sight  to  find  a  large  tract  of  birches  weakened  by  foresl 
fires  in  which  almost  every  tree  has  from  two  to  ten  sporophores 
of  this  fungus  growing  at  various  heights  from  the  ground.  In 
northern  New  England,  New  York,  Michigan,  Wisconsin,  and  Minne- 
sota in  particular,  the  tinder  fungus  (Fomes  f omenta  tins)  is  one  of 
the  commonest  wood-destroying  forms  found  in  deciduous  forests. 
It  grows  with  great  rapidity  in  dead  wood.  Beech  or  birch  trees 
which  have  been  felled  are  rapidly  destroyed  by  the  mycelium  of 
this  fungus.  The  mycelium  will  develop  in  large  masses  from  cut 
surfaces  of  trunks  infected  therewith  when  placed  in  moist  surround- 
ings. This  power  on  the  part  of  the  mycelium  to  flourish  away 
from  the  standing  tree  is  very  characteristic  of  (his  species  and 
also  of  Polyporus  betulinus. 

DECAY   CAUSED    BY   POLYPORUS    BETULINUS. 

So  far  as   known  Polyporus  betulinus  (Bull.)  Fr.  occurs  only  on 
species  of  birch.     It  is  widely  distributed  in  Europe  and  Asia  and 
all  over  the  northern  part  of  North  America,  including  the  northern 
United  States.     In  this  country  it  occurs  on  the  yellow  birch   (B( 
tula  lutea  Michx.  f.),  the  paper  birch   (B.  papyri/era   Marsh.  .  and 
the  white  birch  (B.  populifolia  Marsh.).     The  fruiting  bodies  form 
half-rounded,  conspicuous  brackets,   which  start    as    small   rounded 
knobs,  usually  growing  out  through  a  lenticel.     These  knobs  rapidly 
expand  until  they  form  a  hemispherical  papery  sporophore.     (PL  IX. 
fig.   1.)     The  upper  surface  is  very  smooth,  usually  dirty   white 
color,  with  no  signs  of  marks  or  cracks;    it  resembles  a  very  thick. 
stiff  piece  of  pasteboard.     The  outer  margin  is  round  and  is  usually 
more  or  less  white  wherever  the  thin,  dark  outer  layer  has 
off.     The  rounded  margin  extends  down  on  to  the    lower  \ 
forming  a  decided  ridge  around  it.     The  lower  surf 


**3 

149 


52  DISEASES   OF    DECIDUOUS   FOREST    TREES. 

to  brown  in  color.  The  pores  are  irregularly  jagged  and  toward  the 
outside  assume  a  more  or  less  horizontal  position.  The  sporophores 
grow  to  be  large— in  some  cases  as  much  as  12  inches  in  diameter. 
They  are  annuals  and  are  usually  short  lived,  because  they  are  at- 
tacked by  insects  with  avidity. 

The  decay  caused  by  the  birch  fungus  is  very  similar  to  that  described 
for  Fomesfomentarius.  The  fungus  gains  entrance  through  the  bark, 
probably  through  the  lenticels  or  wounds,  and  starts  growing  in  the 
outer  sap  wood,  progressing  inward  toward  the  center.  (PI.  IX,  fig.  2.) 
The  decayed  wood  is  very  uniformly  yellowish  in  color  and  shows 
numerous  cracks  extending  both  radially  and  tangentially  throughout 
the  mass.  Badly  decayed  wood  crumbles  into  a  fine  powder,  and 
differs  in  this  respect  from  birch  wood  destroyed  by  Fomesfomentarius. 
Mayr  (53)  discusses  the  various  microscopic  changes  caused  by  this 
fungus  in  birch  wood,  treating  not  only  the  morphological  but  also  the 
chemical  changes  induced  by  this  fungus. 

Wherever  birch  trees  are  weakened  either  by  fire  or  other  causes, 
the  birch  fungus  will  attack  them  with  great  rapidity,  and  it  must  be 
considered  as  one  of  the  most  destructive  fungi  to  birch  wood. 

SAP-ROTS  OF  SPECIES  OF  DECIDUOUS  TREES. 

The  line  between  those  fungi  which  are  capable  of  growing  on  dead 
wood  that  has  died  after  being  cut  from  a  living  tree  and  the  fungi 
which  grow  on  dead  wood  of  the  still  living  tree  can  not  be  sharply 
drawn.  Certain  of  the  wood  fungi  cause  disease  while  the  tree  is  still 
standing,  and  where  such  fungi  have  universally  been  found  associated 
with  a  certain  type  of  disease  the  evidence  is  strong  that  the  fungus 
causes  the  disease. 

In  many  recent  descriptions  of  diseases  of  forest  trees  reference  is 
made  to  fungi  which  in  the  opinion  of  the  writers  must  be  considered 
strictly  saprophytic  forms  which  occur  only  on  dead  wood.  A  striking 
instance  of  this  is  Fomes  applanatus  (Pers.)  Wallr.  This  fungus  is 
frequently  found  on  living  trees,  but  a  careful  examination  always 
shows  it  to  be  growing  on  wood  which  is  actually  dead,  and  generally 
on  the  dead  outer  sapwood.  So  far  as  the  writers  have  been  able  to 
observe  Fomes  applanatus  does  not  cause  what  may  be  called  a  disease 
of  living  trees.  The  same  is  true  of  many  other  fungi — for  instance, 
Daedalea  querrina  (L.)  Pers.,  Polystictus  pergamenus  Fr.,  P.  hirsutus 
Fr.,  Poria  vapor  aria  Fr.,  Polyporus  gilvus  Schweinitz,  and  Stereum 
frustulosum  Fr.  It  is  natural  that  observers  should  describe  some 
of  these  fungi  as  being  responsible  for  diseases  of  the  living  tree, 
because  they  occur  frequently  on  standing  trees  which  are  but  par- 
tially alive.  The  writers  believe,  however,  that  most  of  these  forms, 
if  not  all,  will  not  grow  on  a  tree  until  it  has  already  been  so  weakened 


SAP-ROTS    OF    SPECIPJS    OF    DECIDUOUS    TBEE8 

by  other  factors  that  to  all  intents  and  purposes  it  is  dying  or  dead 
with  the  possible  exception  of  cases  where  the  fungi  grow  on  dead 
patches  of  wood  caused  by  some  injury,  as  in  the  case  of  t  rees  injured 
by  fire. 

SAP-ROT    CAUSED    BY   POLYSTICTUS    VERSICOLOR. 

Of  all  the  fungi  which  grow  upon  the  deciduous  spe< ries  of  woods 
after  they  are  cut  from  the  tree  the  most  widely  distributed,  and  in 
many  respects  the  most  destructive,  is  Polystictus  versicolor  (L.)  IV. 
Either  singly  or  in  dense  masses  its  varicolored  sporophores  may  be 
found  on  any  of  the  deciduous  species  in  all  parts  of  the  world 
far  as  known,  this  fungus  is  a  strict  saprophyte,  except  where  it  causes 
the  destructive  heart-rot  of  the  catalpa.  This  fungus  grows  univer- 
sally throughout  the  United  States,  and  probably  in  all  parts  of  the 
world.  It  is  extremely  common  in  Canada,  Mexico,  and  Europe;  it 
is  known  from  Africa  to  Australia,  and  it  has  been  reported  fro  in 
Japan,  the  Canary  Islands,  the  West  Indies,  and  South  America. 

Polystictus  versicolor  is  one  of  the  most  cosmopolitan  species  of  fungi 
known.  It  does  not  seem  to  have  any  preference  for  any  particular 
kind  of  wood,  but  grows  with  almost  equal  readiness,  especially  on 
the  sapwood,  on  every  broadleaf  species  of  wood  (as  distinguished 
from  coniferous  wood)  known.  On  account  of  its  wide  geographical 
range  and  its  ability  to  grow  on  and  destroy  so  many  different  kinds 
of  wood,  it  should  be  regarded  as  the  most  serious  of  all  the  wood- 
rotting  fungi  which  attack  the  dead  wood  of  broadleaf  trees.  It  is 
the  fungus  which  destroys  probably  75  per  cent  or  more  of  the  broad- 
leaf species  of  timber  used  for  tie  purposes.  Wherever  broadleaf 
species  of  wood  are  used  for  fencing,  for  posts  or  poles,  or  for  any  j air- 
pose  where  they  come  in  contact  with  the  soil  they  are  sure  to  be 
attacked  sooner  or  later  by  Polystictus  versicolor. 

The  fruiting  bodies  of  this  fungus  are  extremely  variable,  depending 
upon  the  kind  of  wood  upon  which  they  grow  and  upon  t  he  condi!  ions 
under  which  they  develop.  The  sessile  sporophores  may  grow  singly 
or,  more  usually,  many  of  them  together,  forming  a  series  of  closely 
overlapping  shelves.  As  just  indicated,  they  are  readily  recognized 
by  the  soft,  hairy  upper  surface  with  bands  of  various  colors.  These 
bands  are  usually  white  and  yellow,  although  considerable  variation 
from  both  of  these  colors  will  be  found.  When  young  the  sporophores 
are  fleshy,  but  they  become  tough  and  leathery  when  older.  Tin- 
lower  side  of  the  sporophore  is  generally  snow  white,  and  the  p< 
are  exceedingly  regular  and  minute.  The  body  of  the  sporopl 
is  very  thin,  rarely  exceeding  the  thickness  of  heavy  paper. 

In  the  majority  of  cases  the  sporophores  form  on  a  vertical  surfa<  e 
and  spring  from  a  broad  sheet  of  mycelium  which  covei 

149 


54 


DISEASES   OF    DECIDUOUS   FOREST    TREES. 


surface  of  the  timber  upon  which  they  happen  to  be  growing.  They 
form  readily  in  a  moist  atmosphere.  They  first  appear  as  tiny  .masses 
of  mycelium,  which  grow  out  usually  from  the  medullary  rays,  and 
generally  several  within  a  small  area.  These  small  masses  rapidly 
grow  larger,  until  in  the  course  of  a  few  days  they  have  united  in  a 
single  mass  visible  to  the  naked  eye.  After  they  reach  the  size  of 
one'-eighth  inch  in  diameter,  or  thereabouts,  the  hymenial  layer  begins 
forming  on  the  lower  surface  of  the  knob.  A  mature  fruiting  body 
may  be  formed  in  about  a  week  where  the  fungus  is  in  a  condition  for 
rapid  development. 

The  young  sporophores  seem  at  first  to  grow  perpendicularly  from 
the  surface  from  which  they  protrude,  irrespective  of  whether  this  be 

a  horizontal  or  a 
vertical  surface. 
Very  soon  after 
their  appearance, 
however,  the 
shelves  assume  a 
horizontal  posi- 
tion. Where  wood 
is  placed  in  con- 
tact with  the 
ground,  the  sporo- 
phores are  fre- 
quently cramped 
and  crowded  by 
soil  or  stones,  and 
in  such  cases  the 
growing  m  v  c  e  - 
lium  adapts  itself 
to  the  available 
space  and  pro- 
duces    sporo- 

FlG.  6.— An  oak  railroad  tie  with  fruiting  bodies  of  Polystictus  versicolor.     n"UnT.pc      0f     pvprv 

conceivable  shape  and  size.  It  is  not  at  all  uncommon  to  find  large 
masses  of  the  sporophores  forming  in  the  upper  surfaces  of  cinder 
ballast  on  railroad  tracks.  The  mycelium  in  this  case  binds  the 
individual  cinders  together,  forming  great  clumps  6  or  8  inches  in 
diameter.  Where  two  or  more  sporophores  start  on  a  surface  in  close 
proximity  they  will  as  a  rule  fuse  before  reaching  maturity,  and  as  a 
result  of  this  fusion  long  sheets  may  form  composed  of  two  or  many 
sporophores  which  have  grown  together  laterally  (fig.  6). 

Polystictus  versicolor  usually  starts  its  development  in  some  season 
check,  although  it  may  start  to  develop  on  the  surface  of  a  stick  of 
wood  provided  the  same  is  kept  in  moist  surroundings.     The  spores 

149 


SAP-ROTS    OF    SPECIES    OF    DECIDUOUS    TREES.  55 

germinate  where  a  sufficient  amount  of  water  and  air  is  available, 
and  the  rapidly  growing  hyphse  spread  through  the  wood,  starting 
with  the  medullary  rays.  The  fungus  first  of  all  attacks  the  sugars 
and  starches  stored  in  the  sapwood,  and  then  it  attacks  the  woody 
fiber  itself. 

The  character  of  the  growth  of  Polystictus  versicolor  is  well  shown 
in  figure  6.  In  its  early  stages  the  affected  wood  usually  becomes 
paler  in  color,  and  following  very  soon  after  this  bleaching  effect  the 
wood  begins  to  take  on  a  disintegrated  appearance,  so  that  it  becomes 
what  is  known  popularly  as  "punky."  It  has^  lost  all  of  its  usual 
characteristics  of  hardness  and  strength  and  has  turned  into  a  soft, 
dry,  nonresistant,  pithy  mass,  which  is  usually  more  or  less  straw 
colored. 

The  minute  changes  which  take  place  in  the  wood  fiber  consist  of  a 
rapid  solution  of  various  parts  of  the  woody  structure  in  its  entirety. 
In  other  words,  the  fungus  has  no  special  preference  for  either  the 
lignin  or  cellulose  parts  of  the  cell  wall.  Now  and  then  one  may  find 
a  condition  in  the  last  stages  of  decay  in  which  some  of  the  wood 
fibers  have  become  delignified.  When  such  wood  is  stained  with 
chloriodid  of  zinc  the  whole  wall  of  certain  groups  of  wood  fibers 
seems  to  be  corroded  away.  In  badly  decayed  wood  the  only  parts 
of  the  original  cell  which  remain  recognizable  are  those  parts  of  the 
original  walls  common  to  two  or  three  cells.  Among  the  partiallj 
consumed  fragments  of  the  original  wood  cells  one  may  find  scattering 
complete  cells;  in  fact,  there  is  no  difference  in  the  extent  and  degree 
of  decay  in  different  parts  of  the  same  annual  ring.  The  more  open 
spring  wood  falls  apart  more  readily  because  of  its  porous  nature,  hut 
no  evidence  has  been  obtained  that  it  decays  more  rapidly  than  the 
denser  summer  wood.  The  changes  just  referred  to  are  practically 
the  same  for  all  classes  of  woods  affected. 

Like  all  sap-rotting  fungi  Polystictus  versicolor  is  especially  de- 
pendent for  its  development  upon  the  presence  of  a  sufficient  quantity 
of  water  and  air.  It  will  usually  grow  with  the  greatest  vigor  close 
to  the  surface  of  the  soil.  Its  fruiting  bodies  may  therefore  he 
looked  for  at  or  near  the  ground  line  on  ties,  pole-,  posts,  and  all 
timbers  exposed  to  the  soil.  Where  wood  has  time  to  dry  out  par- 
tially on  the  outside  after  it  is  cut,  the  spores  wall  not  usually  germi- 
nate on  the  outside,  on  account  of  lack  of  water.  Infection  of  such 
partially  dried  wood  usually  takes  place  through  someseason  check. 

This  fungus  may  start  development  in  a  stick  of  wood  within  a  few 
weeks  after  it  has  been  cut;  or,  in  other  words,  shortly  after  the 
becomes  sufficiently  dry  on  the  outside  to  form  season  checks.    Alt 
it  has  once  gained  entrance  below  the  surface,   the  n, 
grow  vigorously  in  the  wood  and  give  absolutely  no 

149 


56  DISEASES    OF    DECIDUOUS   FOREST    TREES. 

presence  on  the  outside  until  the  wood  has  become  sufficiently 
decayed  to  permit  of  the  formation  of  sporophores,  which  then  usually 
form"  by  growing  out  through  the  season  checks  to  the  outside  air. 
It  is  on  account  of  its  ability  to  produce  decay  in  the  interior  of  the 
stick  of  wood  that  this  fungus  is  so  very  destructive,  and  it  is  for 
this  reason  that  the  greatest  care  should  be  taken  to  guard  against  its 
possible  entrance.  In  moist  climates  the  fruiting  bodies  will  form 
above  the  ground  on  wood  which  may  be  several  feet  above  the  soil. 
Where  wood  has  a  chance  to  have  air  circulate  around  it  continuously, 
however,  the  possibilities  that  it  will  become  infected  with  this  fungus 

are  remote. 

The  decay  which  Polystictus  versicolor  brings  about  in  wood  is 
usually  confined  for  a  year  or  more  to  the  sapwood,  and  in  many 
species  it  is  wholly  confined  to  the  sapwood.  This  is  true  of  such 
trees  as  have  their  heartwood  sharply  differentiated  from  their  sap- 
wood,  as  in  the  oaks  (Quercus  spp.),  black  walnut  (Juglans  nigra  L.), 
red  gum  (Liquidamoar  styraciflua  L.),  etc.  In  woods  where  the 
differentiation  between  heart  and  sap  wood  is  indistinct,  as  in  the 
tulip  poplar  (Liriodendron  tulipifera  L.),  willows  (Salix  spp.),  and 
Cottonwood  (Populus  deltoides  Marsh.),  the  fungus  brings  about  the 
destruction  of  the  sapwood  with  great  rapidity,  and  even  destroys 
the  heartwood,  although  this  takes  place  more  slowly.  Between 
these  two  extremes  there  are  many  gradations.  Sapwood  of  the 
white  ash  (Fraxinus  americana  L.),  yellow  birch  (Betula  lutea 
Michx.  f.),  and  beech  (Fagus  atropunicea  (Marsh.)  Sudworth)  is 
rapidly  destroyed,  but  the  heartwood  resists  the  attacks  of  this 
fungus  for  a  considerable  period  of  time,  although  not  so  long  as  does 
the  neartwood  of  the  oaks.  The  rate  at  which  the  sapwood  of  differ- 
ent broadleaf  species  decays  presents  little  variation.  It  may  be 
stated  as  a  general  rule  that  the  sapwood  of  all  trees  is  very  suscepti- 
ble to  the  attacks  of  Polystictus  versicolor  and  that  where  any  differ- 
ence in  the  resisting  power  of  such  woods  to  this  fungus  occurs  it  will 
be  in  favor  of  the  heartwood. 

Measures  for  preventing  or  arresting  the  development  of  Polystictus 
versicolor  will  be  considered  later,  together  with  other  sap-rotting 
fungi,  because  preventives  which  apply  to  this  fungus  will  apply  to 
practically  all  of  the  sap-rotting  forms. 

SAP-ROT    CAUSED    BY    POLYSTICTUS    PERGAMENUS 

A  second  form  of  sap-rot  of  great  importance  is  caused  by  Poly- 
stictus pergamenus  Fr.  This  fungus,  while  usually  found  on  dead 
wood,  may  now  and  then  occur  on  living  trees  where  these  have  been 
severely  injured.  It  is  one  of  the  forms  which  frequently  appear 
on  standing  trees  after  forest  fires  have  killed  certain  parts  of  the 

1   l!> 


SAP-ROTS    OF    SPECIES    OF    DECIDUOUS    TREES. 


57 


trunk.  The  forest  fire  may  not  seem  to  have  injured  the  tree  at  the 
time,  although  the  heat  may  have  been  sufficient  to  kill  the  cambium 
layer  over  a  considerable  area.  The  bark  over  such  areas  dries  out 
and  cracks,  and  it  is  in  such  dead  bark  that  this  fungus  finds  a  favor- 
able entrance.  Within  a  few  months  after  the  injury  the  sporophores 
of  Polystictus  pergamenus  are  found  growing  on  the  dead  hark,  and 
the  decay  caused  by  the 
fungus  extends  rapidly 
throughout  the  deadened 
area  (fig.  7).  In  almost 
any  burnt  area  of  decidu- 
ous forest  one  may  find 
many  of  the  standing  trees 
after  a  year  or  two  bearing 
large  masses  of  the  sporo- 
phores of  this  fungus. 

Polystictus  pergamenus  is 
universally  distributed 
throughout  the  United 
States  and  Canada,  and  it 
is  known  from  various 
points  in  South  America. 
It  grows  on  practically  all 
the  deciduous  species  of 
wood.  It  is  very  common 
on  species  of  oak  and  has 
been  collected  by  the  writ- 
ers on  the  following  woods : 
Red  gum  {Liquidambar 
styracifiua  L.),  white  oak 
(Quercus  alba  L.),  scarlet 
oak  (Q.  coccinea  Muench.), 
red  oak  (Q. rubra Jj.),  black- 
jack oak  (Q.  marilandica 
Muench.),  shingle  oak  (Q. 
imbricaria  Michx.),  sugar 
maple  (Acer  saccharum 
Marsh.),  silver  maple  (A  saccharinum  L.),  red  maple  ( . .  I .  rubrum  I 
yellow  birch  (Betula  lutea  Michx.  f.),  chestnut  (Castanea  dentate 
(Marsh.)  Borkh.),  shagbark  hickory  (Hicoria  ovata  (Mill.)  Britton  . 
tulip  poplar  (Liriodendron  tulipifera  L.) ,  black  cherrj  ' ' 
Ehrh.),  beech  (Fagus  atropunicea  (Marsh.)  Sudworth)3  and  willow 
(Salix  sp.). 

149 


Fig.  7. — Aliving  tree  of  red  oak  the  bark  ofwhicb  was 
killed  by  fire.  The  fungus  Polystictus  pergamenus  is 
rapidly  rotting  thesapwood  beneath. 


58  DISEASES   OF    DECIDUOUS   FOREST    TREES. 

The  general  appearance  of  wood  decayed  by  this  fungus  is  very 
similar  "to  that  destroyed  by  Polystictus  versicolor.  The  microscopic 
changes  differ  in  certain  respects.  A  cross  section  of  oak  wood  cut 
so  as  tp  include  both  healthy  and  badly  decayed  wood  shows  areas 
of  the  wood  fibers,  especially  in  the  summer  wood  of  the  annual  ring, 
which  are  colorless,  while  the  other  parts  of  the  section  are  more  or 
less  yellow.  The  colorless  parts  are  the  rotted  regions,  and  in  very 
badly  affected  wood  they  may  include  all  of  the  wood  fibers  in  an 
annual  ring.  The  vessels  and  the  medullary  ray  cells,  however,  retain 
their  color  and  appear  unaffected.  When  stained  with  cellulose 
reagents  like  chloriodid  of  zinc  the  colorless  areas  stain  deep  blue. 
From  this  it  appears  that  the  fungus  removes  the  lignin  elements 
from  the  cell  walls.  In  the  worst  affected  areas  the  cells  are  broken 
down  still  further  and  the  walls  appear  broken  and  corroded,  so  that 
little  remains  except  small  fragments  of  the  cell  walls  with  the 
pieces  of  the  middle  lamella  which  are  located  at  the  corners  of  these 
cells  embedded  within  them,  and  the  whole  held  together  by  masses 
of  fine  fungous  hyphse.  The  medullary  ray  cells  resist  the  action  of 
the  fungus  longer  than  any  other  part,  very  much  as  is  the  case  in  the 
form  of  decay  caused  by  Polystictus  versicolor. 

The  rate  of  decay  caused  by  this  fungus  is  very  much  like  that 
described  for  Polystictus  versicolor.  Small  pieces  of  oak  wood  inocu- 
lated with  spores  of  the  fungus  have  been  completely  rotted  in  about 
three  months.  The  rate  of  decay  varies  with  the  amount  of  water 
left  in  the  wood,  the  air  supply,  and  the  temperature. 

The  relative  resistances  of  heartwood  and  sapwood  to  the  attacks 
of  this  fungus  are  very,  similar  to  those  already  referred  to  for  Poly- 
stictus versicolor,  and  the  same  may  be  said  of  the  relative  resisting 
power  of  different  species  of  woods,  so  far  as  known  at  this  time. 

The  fruiting  bodies  of  Polystictus  pergamenus  occur  throughout  any 
deciduous  forest  tract.  A  large  number  usually  grow  together,  one 
above  the  other,  and  not  infrequently  they  are  joined  laterally  so  as 
to  form  long  series  of  shelves.  The  body  of  the  pileus  is  leathery  and 
rigid;  the  top  is  concentrically  sulcate,  generally  white  when  young, 
growing  grayish  when  older;  the  upper  surface  is  slightly  hairy;  the 
lower  surface  is  generally  purplish  in  color;  the  pores  are  small  and 
the  intervening  walls  become  much  torn  and  lacerated,  so  that  in 
older  specimens  they  resemble  teeth  or  spines. 

SAP-ROT    CAUSED    BY   FOMES    APPLANATUS. 

In  a  recent  paper  Heald  (38)  describes  a  disease  of  the  cottonwood 
due  to  Fomes  applanatus  (Pers.)  Wallr.,  which  he,  however,  calls 
Elfvingia  megaloma  (Lev.)  Murrill.  He  finds  that  cottonwood  trees 
are  affected  with  a  disease  which  attacks  both  heart  and  sap  wood  and 

149 


SAP-ROTS    OF    SPECIES    OF    DECIDUOUS    TREES. 


59 


results  in  their  gradual  destruction,  ultimately  causing  the  death  of 
the  entire  tree.  The  injury  to  the  wood  is  only  local,  occurring  gen- 
erally near  the  base  of  the  trunk.  The  fungus  is  said  to  enter  the 
trunk  through  injuries  near  the  ground  line  or  through  wounds  on  the 
roots,  and  " spreads  upward  through  the  entire  wood,  reachilig,  in 
specimens  observed,  the  height  of  10  feet.  The  entire  wood  »,;'  the 
lower  portion  of  the  trunk  becomes  thoroughly  infected  before  the 
fungus  obtains  sufficient  vigor 
to  produce  its  external  fruiting 
bodies.  In  this  condition  the 
wood  is  rendered  very  brittle, 
and  the  tree  thus  affected  is 
poorly  fitted  to  withstand  the 
force  of  the  wind  in  severe 
storms"  (38). 

The  diseased  wood  is  char- 
acterized by  the  appearance  of 
numerous  localized  pockets, 
separated  from  one  another  by 
wood  which  the  fungus  has 
evidently  not  been  able  to  de- 
stroy. Heald  states  that  the 
fungus  is  probably  only  a  facul- 
tative parasite  and  "is  not 
able  to  attack  young,  healthy 
trees,  but  that  it  can  become 
parasitic  on  older  trees  in  which 
the  vitality  has  been  consid- 
erably lowered,  or  that  have 
reached  the  maximum  of  their 
development." 

The  writers  have  repeatedly 
observed  this  form  of  decay  in 
the   cottonwood,  but    in   their 
experience    it     usually    starts 
near  the  base  of  the  trunk  in 
large  wounds  caused  by  fire  or 
otherwise.     On  that  account  they  are  not  inclined  to  call  this  di 
of  the  cottonwood  a  disease  in  the  sense  in  which  the  decaj  -  induced 
by  Fomes  igniarius,  F.  fraxinopliilus,  and  others  are  diseases.      I  bere 
are  a  large  number  of  species  of  fungi  which,  like  Fomes  applan 
grow  on  dead  wood  and  which  may  now  and  then 
trees.     All  of  these,  including  Fomes  applanatus,  <•■  jus 

well  and  apparently  better  on  wood  after  it  has  been  cut  from  liv- 

149 


Yig.  8.— A  dead  stub  of  a  maple  tree  bearing  fruiting 

bodies  of  the  sap-rot  fungus  (Fome*  opptoi 


60 


DISEASES    OF    DECIDUOUS    FOREST    TREES. 


ing  trees,  and  should,  in  the  opinion  of  the  writers,  be  considered  as 
saprophytic  forms.      (See  fig.  8.) 

DECAY    CAUSED    BY    STEREUM    FRUSTULOSUM. 

Stereum  frustulosum  (Pers.)  Fr.  and  other  species  of  Stereum 
cause  the  destruction  annually  of  large  quantities  of  structural  tim- 
bers. The  fruiting  bodies  of  this  fungus  are  very  insignificant  and 
generally  escape  the  attention  of  the  casual  observer.  They  appear 
in  the  form  of  small,  slightly  elevated  gray  spots  on  the  surface  of 
decaying  wood.  In  the  majority  of  instances  they  look  like  sheets 
of  cracked  mud,  the  individual  pieces  separated  by  the  cracks  vary- 


Fig.  9. 


A  piece  of  oak  timber  rotted  by  Stereum  fruxtulosum.    The  fruiting  bodies  are  the  lighter 
colored,  irregular,  small  bodies  which  are  seen  thickly  scattered  over  the  surface. 


ing  in  size  from  one-sixteenth  to  one-fourth  of  an  inch  in  diameter. 
Figure  9  shows  a  piece  of  red  oak  (Q-uercus  rubra  L.)  with  the  fruit- 
ing bodies  of  this  fungus. 

Wood  decayed  by  Stereum  frustulosum  can  always  be  recognized 
by  the  peculiar  pocket-like  formation  in  the  mass  of  the  wood.  Fungi 
like  Polystictus  versicolor  produce  a  form  of  rot  in  which  the  entire 
mass  of  the  wood  is  affected.  Stereum  frustulosum,  on  the  other 
hand,  causes  changes  in  the  wood  fiber  in  localized  areas  of  the  wood. 
The  holes  are  more  or  less  lens  shaped  and  are  separated  from  one 
another  by  sound  layers  of  wood  fiber.  The  lining  of  the  holes  is 
usually  composed  of  a  layer  of  white  cellulose  fibers.     Stereum  frustu- 

149 


SAP-ROTS    OF    SPECIES    OP    DECIDUOUS    TREES.  61 

losum  occurs  on  practically  all  of  the  oaks,  and  probably  on  other 
broadleaf  species.  It  is  sometimes  found  growing  in  wounds  on  liv- 
ing trees,  but  is  strictly  confined  to  dead  wood.  It  is#widely  dis- 
tributed in  the  United  States  and  is  one  of  the  chief  funei  destroying 

■ 

oak  wood. 

SAP-ROT    CAUSED    BY    DAEDALEA    QUERCINA. 

One  of  the  most  important  enemies  of  structural  oaks  (Quercua 
spp.)  and  chestnut  (Castanea  dentata  (Marsh.)  Borkh.)  is  Daedatea 
quercina  (L.)  Pers.  Plate  X  shows  an  end  view  of  a  white-oak  tie 
with  the  sporophores  of  this  fungus;  also  a  section  of  the  same  tie  2 
feet  from  the  end.  This  fungus  has  a  world-wide  distribution.  '  It  is 
one  of  the  most  common  forms  on  oak  and  chestnut  logs,  ties,  tele- 
graph poles,  fence  posts,  bridge  timbers,  etc.,  all  of  which  it  desl  roys 
with  rapidity.  The  conditions  favoring  the  spread  of  this  fungus, 
the  manner  in  which  the  wood  is  infected,  and  the  rate  of  growth  are 
in  a  general  way  very  similar  to  those  described  for  the  two  preceding 
fungi.  The  sporophores  form  either  singly  or  in  groups.  They  are 
sometimes  found  growing  out  from  large  wounds  upon  the  sapwood 
of  standing  trees;  hence,  this  fungus  has  been  frequently  described 
as  one  causing  a  disease  of  living  trees.  The  sporophores  are  tough 
and  rigid,  with  a  corky  consistency.  They  are  first  white  in  color, 
but  gradually  turn  darker  to  a  gray;  the  upper  surface  is  zonate  :  the 
pores  are  elongated  and  have  a  wavy  outline. 

The  wood  decayed  by  this  fungus  is  generally  moisi  and  mushy, 
but  on  drying  becomes  harder,  although  when  rubbed  between  the 
fingers  it  crumbles  into  a  fibrous  mass. 

OTHER    SAP-ROTTING    FUNGI. 

In  addition  to  the  sap-rotting  fungi  referred  to  there  are  a  large 
number  which  grow  more  or  less  frequently  on  broadleaf  species  ol 
wood.  Their  number  is  so  large  that  it  is  impossible  to  refer  to  all 
of  them  here,  and  only  a  few  of  the  more  typical  ones  can  be  men- 
tioned. Among  these  are  the  following:  Polystictus  hirsutus  Fr.,  P. 
sanguineus  (L.)  Mey.,  P.  cinnabarinus  (Jacq.)  Fr.,  Poria  subacida 
Peck.,  P.  vaporaria  Fr.,  Poly-poms  betulinus  (Bull.)  Fr.,  P.  gilvus 
Schwein.,  P.  adustus  (Willd.)  Fr.,  Lenzites  corrugate  Klotzsch,  /.. 
vialis  Peck.,  and  L.  betulina  (L.)  Fr. 

All  of  these  forms  and  many  others  grow  singly  or,  more  frequently, 
in  masses  on  dead  wood,  which  they  destroy  with  varying  d< 
rapidity.     The  manner  in  which  they  enter  1 1  ie  wood  and  the  rai 
growth  differ  slightly  for  the  different  forms,  but  for  practical  pui 
poses  they  need  not  be  distinguished  from  Polystictus  >■ 
P.  pergamenus.     Detailed  studies  of  most  of  these  I 
be  made.     Some  of  the  forms  which  attack  beech  woo 
been  described  by  Tuzson  (103). 

149 


52  DISEASES   OF    DECIDUOUS   FOREST    TREES. 

DECAY  OF  STRUCTURAL  TIMBER. 

After  the  wood  from  any  of  the  broadleaf  trees  has  been  cut  from 
the  tree  and  it  is  exposed  to  the  air  or  soil,  decay  occurs  sooner  or 
later.  Different  species  show  a  varying  power  of  resistance  to  decay 
when  thus  exposed,  and  as  a  result  of  this  difference  these  woods  are 
usually  classed  into  long-lived  and  short-lived  woods.  The  long- 
lived  woods  possess  natural  inherent  qualities  which  enable  them  to 
resist  the  attack  of  decay  for  a  comparatively  long  period.  In  com- 
parison with  many  coniferous  woods,  the  broadleaf  species  have  a 
very  much  smaller  power  to  resist  decay,  and  the  number  of  them 
which  are  long  lived  is  rather  few.  Among  those  woods  which  may 
be  considered  very  long  lived  are  the  catalpa  {Catalpa  speciosa  War- 
der), black  locust  (Robinia  pseudacacia  L.),  and  Osage  orange  (Toxy- 
lon  pomiferum  Raf.).  Woods  like  the  white  oak  (Quercus  alba  L.), 
chestnut  {Castanea  dentata  (Marsh.)  Borkh.),  and  shagbark  hickory 
{Hicoria  ovata  (Mill.)  Britton)  come  next  in  durability;  while  among 
the  very  short  lived  woods,  the  willows  (Salix  spp.),  cottonwood 
(Populus  deltoides  Marsh.),  beech  (Fagus  atropunicea  (Marsh.)  Sud- 
worth),  and  tupelo  gum  (Nyssa  aquatica  L.)  may  serve  as  examples. 

CAUSES    OF    DECAY. 

The  decay  of  wood  after  it  has  been  cut  from  the  living  tree  may 
be  due  to  a  number  of  causes.  It  may  crumble  away  because  of 
influences  usually  referred  to  as  "  weathering."  Wood  fiber  when 
exposed  to  the  air  and  to  frequent  wetting  by  rain  is  worn  away 
mechanically,  giving  the  surface  a  roughened  appearance.  The 
wood  of  most  broadleaf  species  after  being  exposed  turns  grayish 
white  in  color  on  the  outside,  due  to  the  separation  of  groups  of  wood 
fibers  which  stand  out  from  the  surface  and  give  it  a  more  or  less 
hairy  appearance. 

The  principal  cause  of  decay  is  the  growth  of  certain  saprophytic 
fungi  in  the  wood  fibers,  which  as  a  result  of  their  growth  bring  about 
changes  in  the  wood  which  alter  its  structure  and  tensile  quality. 

FACTORS    FAVORING   DECAY. 

The  factors  which  favor  the  decay  of  wood  in  general  have  been 
repeatedly  referred  to  (79,  81)  as  (1)  a  certain  amount  of  water,  (2) 
a  certain  amount  of  heat,  (3)  a  certain  amount  of  air,  and  (4)  a  cer- 
tain amount  of  food  supply.  Where  one  or  more  of  these  four  factors 
are  absent,  decay  will  not  be  possible,  because  the  growth  of  the 
wood-destroying  fungi  is  prevented. 

149 


DECAY    OF    STRUCTURAL    TIMBER. 


63 


RATE    OF   DECAY. 

The  rate  of  decay  varies  according  to  the  species  of  wood  and  the 
part  of  the  tree  from  which  it  is  taken.  Sapwood  decays  vcrv  much 
more  rapidly  than  heartwood.  In  many  broadleaf  species  the  sap- 
wood  may  be  attacked  by  one  or  more  of  the  wood-destroying  fungi 
within  a  few  weeks  after  the  wood  is  cut.  The  most  notable  exam- 
ples of  the  rapid  decay  of  the  sapwood  are  to  be  found  in  timbers  like 
beech  (Fagus  atropunicea  (Marsh.)  Sudworth),  red  oak  {Quercus 
rubra  L.),  and  chestnut  (Castanea  dentata  (Marsh.)  Borkh.).  The 
relation  which  the  presence  of  organic  matter  in  the  sapwood  has  to 
its  decay  has  been  a  much  discussed  question.  It  has  generally  been 
thought  that  sapwood  will  decay  most  rapidly  when  cut  from  the 
tree  during  the  period  when  the  organic  matter,  such  as  starches  and 
sugars,  is  present  in  the  largest  quantities  and  is  being  actively 

so 

eo 

\7° 
I 

Q 


\zo 


■  /ao3 


1    1 

Z.  FS-f-rvo 

»"/y/i^"  /?/ro  oix 

\ 

\ 

\ 

^ 

1 

^ 

». 

j£m 

,^"' 

"»a 

»*.. 

^ 

•- 

1 

II 


-/90f 


fUTU 


Fig.  10.— Diagram  showing  relative  rate  of  decay  of  2,400  pieces  of  "hill"  and  "bottom"  red  oak. 

Countings  made  April  26,  1906. 

formed  by  the  tree;  that  is,  during  the  spring  and  early  summer. 
This  has  given  rise  to  the  almost  universal  practice  of  requiring  struc- 
tural timber  to  be  cut  during  the  winter  period,  in  order  to  insure 
a  long  life. 

From  a  number  of  experiments  made  on  a  large  scale  with  red  oak 
the  writers  found  that  the  idea  that  material  cut  in  the  winter  un- 
less susceptible  to  fungous  attack  certainly  did  not  hold  in  all  ca 
Reference  to  figure  10  shows  that  red-oak  timbers  cut  in  November, 
1903,  decayed  more  rapidly  than  did  similar  timbers  cut  from  the 
same  land  and  piled  in  the  same  locality  in  June,  1903.  A\  hile  this 
single  experiment  does  not  necessarily  show  that  summer-cut  wood 
is  preferable  to  winter-cut  wood,  it  indicates  very  clearly  that  many 
of  the  ideas  held  for  a  long  time  as  to  the  relative  value  o{  winter  and 
summer  cut  wood  deserve  more  extensive  and  careful  in 


79152— Bui.  149—09- 


54  DISEASES   OF    DECIDUOUS   FOREST    TREES. 

MANNER    OF    INFECTION. 

One  of  the  most  practical  questions  in  connection  with  the  decay 
of  sapwood  of  broadleaf  species,  as  well  as  of  conifers,  deals  with 
the  manner  in  which  the  sapwood  becomes  infected  with  the  fungus. 
With  the  possible  exception  of  some  of  the  fungi  referred  to  in  a  pre- 
vious part  of  the  bulletin,  such  as  Fomes  igniarius  and  Polyporus 
sulphureus,  most  of  the  fungi  which  bring  about  the  decay  of  struc- 
tural timber  do  not  grow  in  living  trees.  The  heart  wood  of  the  liv- 
ing tree  is  accordingly  free  from  the  supposed  germs  of  decay,  and 
wherever  any  decay  does  take  place  the  spores  of  the  fungi  responsi- 
ble for  the  same  must  get  into  the  wood  from  the  outside. 

Although  this  has  been  very  definitely  shown  to  be  the  case,  there 
is  still  a  very  widespread  belief  among  timbermen  that  decay  starts 
in  the  interior  of  the  stick.     This  has  arisen  from  the  fact  that  pieces 


Fig.  11.— Cross  section  of  an  oak  railroad  tie  rotted  by  one  of  the  sap-rot  fungi.    Note  the  season  crack 
through  which  the  fungus  obtained  entrance  to  the  interior. 

of  wood  may  appear  perfectly  sound  on  the  outside  and  still  may  be 
wholly  decayed  in  the  inner  part.  In  figure  11a  striking  example  of 
this  is  shown.  This  figure  shows  a  section  taken  from  a  piece  of 
"bottom"  red  oak  cut  in  Ma}',  1904.  The  timber  was  piled  in  the 
open,  and  the  section  here  shown  was  taken  in  1906.  It  will  be 
noted  that  the  outer  quarter  of  an  inch  of  wood  appears  perfectly 
sound  and  that  immediately  inside  this  sound  layer  the  wood  has 
been  completely  decayed.  There  was  absolutely  no  external  sign  on 
this  timber  which  would  indicate  that  it  was  not  sound  throughout. 
Instances  of  this  kind  are  numerous  and  they  naturally  give  rise  to 
much  apprehension  on  the  part  of  the  purchaser  of  timber,  because 
it  is  not  practicable  to  cut  into  timbers  for  the  purpose  of  deter- 
mining whether  they  are  sound  on  the  inside. 

149 


DECAY    OF    STRUCTURAL    TIMBEB.  65 

The  explanation  for  this  form  of  sap  decay  is  briefly  as  follows: 
When  the  stick  of  wood  (fig.  11)  was  cut  it  was  perfectly  greeD  and 
full  of  water.  It  was  piled  so  that  it  was  exposed  on  all  sides  to  the 
wind  and  sun.  As  a  result  of  this  exposure  the  outer  layers  of  i  he  wood 
fiber  dried  very  rapidly,  and  the  amount  of  water  left  in  the  outer 
layers  was  insufficient  for  the  development  of  the  wood-destroying 
fungus.  As  a  result  of  the  dry ing,  small  season  checks  Formed  on 
the  outside,  one  of  which  will  be  noticed  in  the  middle  at  the  top  of 
the  photograph.  The  season  check  penetrated  into  the  interior  for 
an  inch  or  two;  then  some  of  the  spores  of  the  fungus  lodged  in  it  and 
there  was  still  sufficient  moisture  to  enable  the  spore  t<>  germinate 
and  grow.  The  fungus  then  rapidly  spread  through  the  wet  sapwood 
near  the  bottom  of  the  season  check,  bringing  about  the  decay  shown 
in  the  figure.  This  decay  would  have  gone  on  until  all  of  the  sapwood 
was  destroyed,  and  fruiting  bodies  would  then  have  formed  on  the 
outside  in  one  of  the  season  checks. 

A  very  familiar  instance  of  this  kind  of  internal  decay  can  be  found 
in  any  forest  where  the  stumps  of  trees  are  examined  a  year  or  more 
after  the  trees  have  been  felled.  The  cut  surface  of  the  stump  will 
appear  season  checked,  but  otherwise  sound.  When  bored  into. 
however,  the  wood  within  about  a  half  inch  of  the  upper  surface  «»1 
the  stump  will  usually  be  found  completely  decayed.  The  realiza- 
tion that  sap-rot  in  timber  is  due  almost  wholly  to  the  action  of  fungi 
the  spores  of  which  enter  through  season  checks  and  develop  in  the 
sapwood  when  it  is  not  allowed  to  dry  out  is  one  of  the  most  impor- 
tant practical  considerations  in  connection  with  the  entire  study  of 
the  diseases  of  woods. 

SUSCEPTIBILITY    TO    DECAY. 

The  same  species  of  wood  will  show  differing  tendencies  toward 
decay,  according  to  the  localities  in  which  the  trees  are  grown.     This 
is  well  illustrated  by  the  difference  in  lasting  power  which  is  found 
in  so-called  "hill"  and  "bottom"  red  oak  (Quercus  rubra  L.).      Hill 
red  oak  grows  very  much  more  slowly  than  bottom  red  oak,  forming 
a  denser  grained,  heavier  wood,  which  is  less  permeable  by  water.     In 
figure  10  the  results  of  an  extensive  experiment  comparing  hill  and 
bottom  red  oak  are  shown.     This  figure  shows  the  results  of  exposing 
some  2,400  pieces  of  hill  and  bottom  red  oak.     One  hundred  pi< 
were  cut  every  month,  beginning  in  January.   1903,  and  continuing 
until  December,  1904.     Two  tracts  of  land  were  selected     one  on 
which  the  hill  variety  grew  and  the  other  some  50  miles  av 
which  a  dense  bottom  red-oak  stand  was  growing.     All  of  th<i  I 
bers  were  piled  in  a  similar  manner  and  were  left  for  observatio 

149 


66  DISEASES   OF    DECIDUOUS   FOREST    TREES. 

With  the  exception  of  several  months'  cut  of  the  hill  red  oak,  the 
programme  was  carried  out  for  two  years.  The  numbers  at  the  left 
of  the  figure  indicate  the  percentage  of  timbers  upon  which  masses 
of  wood-destroying  fungi  were  growing  and  which  were  obviously  de- 
cayed to  a  greater  or  less  extent.  Tso  account  could  be  taken  of 
internal  decay,  as  just  referred  to,  where  no  sporophores  were  formed, 
because  it  was  not  possible  to  cut  into  the  pieces. 

Figure  10  shows  one  thing  very  strikingly,  namely,  the  greater  per- 
centage of  decay  in  bottom  red  oak  than  in  hill  red  oak.  This  is  espe- 
cially noticeable  for  certain  months — for  instance,  August  and  Sep- 
tember, 1903,  where  in  the  case  of  the  bottom  red  oak  28  and  42  per 
cent,  respectively,  were  decayed,  while  with  the  hill  red  oak  but  6 
per  cent  were  decayed.  When  exposed  for  but  a  brief  period  of  time, 
the  difference  between  the  two  timbers  is  not  so  striking,  as  is  shown 
by  the  last  months  included  in  figure  10.  This  is  readily  explained 
by  the  fact  that  the  decay  had  not  advanced  far  enough  for  the 
formation  of  fruiting  bodies  of  the  fungus,,  except  in  those  timbers 
where  infection  first  took  place.  If  the  timbers  cut  in  June,  July, 
August,  etc.,  had  been  left  as  long  as  those  cut  the  year  before,  the 
difference  would  probably  have  been  equally  as  striking  as  during 
1903. 

PREVENTIVE    METHODS. 

The  prevention  of  decay  due  to  one  or  the  other  of  the  fungi  just 
described  may  be  brought  about  in  one  of  two  ways:  First,  by  placing 
the  wood  under  such  conditions  that  the  wood-destroying  fungi  can 
not  develop;  second,  by  treating  the  wood  with  chemical  preserva- 
tives which  act  as  poisons  for  the  wood-rotting  fungi.  Both  of  these 
methods  are  successful,  and  it  is  usually  necessary  to  employ  both 
in  conjunction. 

One  of  the  most  important  preliminary  steps  in  the  handling  of 
timber  after  it  is  cut  from  the  log  is  to  dry  it  out  as  rapidly  as  possible. 
The  drying  process  should  aim  to  remove  the  water  as  equably  as 
possible  from  all  parts  of  the  stick,  so  that  excessive  checking  may 
not  result.  Where  the  drying  does  not  take  place  uniformly,  infec- 
tion by  sap-rotting  fungi  occurs,  as  has  been  most  strikingly  shown 
(fig.  11).  All  wood  should  be  kept  from  contact  with  the  soil  for  a 
certain  period  after  it  is  cut  from  the  tree,  and  only  after  it  has  been 
thoroughly  dried  should  it  be  thus  exposed. 

Where  wood  is  to  be  chemically  treated,  especially  those  species 
which  are  very  susceptible  to  sap-rotting  fungi,  like  the  red  oak 
(Quercus  rubra  L.),  beech  (Fagus  atropunicea  (Marsh.)  Sud worth), 
red  gum  (Liquidambar  styraciflua  L.),  etc.,  the  greatest  care  should 
be  used  to  pile  the  wood  so  that  no  two  pieces  shall  touch  more  than 
is  absolutely  necessary.     Timbers  should,  furthermore,  not  be  piled 

149 


DECAY    OF    STRUCTURAL    TIMBEB.  67 

for  too  long  a  period,  because,  so  far  as  known  up  to  this  time,  the 
only  safe  method  for  avoiding  the  chance  of  getting  sap-rotted  pii 
such  as  shown  in  figure  11, is  to  chemically  trcit  the  wood  before  the 
fungus  has  had  an  opportunity  of  getting  a  foothold. 

Where  large  timbers  are  used,  it  is  always  well  to  lessen  the  chances 
of  internal  decay,  or  so-called  dry-rot,  by  building  composite  timbers. 
Some  recent  striking  instances  were  noted  in  a  large  building  where 
12  by  12  inch  oak  timbers  were  used  for  posts  and  beams.  One  of  the 
wood-destroying  fungi  had  gained  entrance  through  the  lower  ends  of 
some  of  these  vertical  posts,  had  grown  up  through  them  w  ithoul  any 
signs  on  the  outside,  and  had  infected  the  horizontal  beams.  .  The 
decay  had  proceeded  from  the  cellar  to  the  tenth  story  of  the  Large 
factory  building.  The  discovery  of  the  decayed  condition  was  made 
when  a  hole  was  bored  into  one  of  the- timbers  for  the  purpose  of  in- 
serting a  screw;  the  timbers  were  then  removed,  and  it  was  found 
that  they  had  entirely  decayed  with  the  exception  of  a  shell  of  about  an 
inch  in  thickness  on  the  outside.  In  reconstructing  this  building  oak 
timbers  were  used,  but  instead  of  using  12  by  12  inch  pieces  for  posts 
they  were  made  of  four  3  by  12  inch  pieces  bolted  together.  The 
chances  for  internal  decay  of  such  posts  will  be  much  lessened.  The 
most  efficient  method  for  preventing  the  decay  of  timber  consists  in 
chemical  treatment.  References  to  this  subject  will  be  found  in  the 
bibliography  appended  hereto  (12,  13,  14,  15,  28,  29,  64,  81.  85,  86, 
90,  91,  103,  108). 

140 


BIBLIOGRAPHY. 

1.  Arthur,  J.  C.     Bot.  Gaz.,  29:  275,  1900,  Jour.  Myc,  12:  16,  L906,  and  11:  11, 

1908. 

2.  Atkinson,  G.  F.     Oedema  of  apple  trees.    N.  Y.  (Cornell)  Agr.  Expt.  Sta.,  Bui. 

61:  292-302,  1893. 

3.  Some  wood-destroying  fungi.     Geol.  Survey  La.,  Special  Rept.  9: 

338,  1899. 

4.  Mushrooms  edible  and  poisonous,  p.  194,  1900. 

5.  Studiesof  some  shade-tree  and  timber-destroying  fungi.     N.  Y.  (Cornell) 

Agr.  Expt.  Sta.,  Bui.  193:  199-235,  1901. 

6.  — —     Studiesof  some  tree-destroying  fungi.     Trans.  Mass.  Hort.  Soc.  for  L902, 

pp.  109-130. 

7.  Buckhout,  W.  A.     The  effect  of  smoke  and  gas  upon  vegetation.     Pa.  Dept. 

Agr.,  Rept.  for  1900-1901,  pp.  321-322,  pt.  I. 

8.  Buller,  A.  H.  Reginald.     The  destruction  of   wooden  paving  blocks  by  the 

fungus  Lentinus  lepideus  Fr.     Jour.  Econ.  Biol.,  1:  1-12,  pis.  I  -2,  L905. 

9.  The  biology  of  Polyporus  squamosus  Huds.,  a  timber-destroying  fungus. 

Jour.  Econ.  Biol.,  1:  101-138,  pis.  5-9,  1906. 

10.  Butler,  E.  J.     Some  Indian  forest  fungi.     Indian  Forester,  31 :  487-496,  54s 

611-617,  670-679,  1905. 

11.  Chandler,  W.  H.     The  winter  killing  of  peach  buds  as  influenced  by  previous 

treatment.     Mo.  Agr.  Expt.  Sta.,  Bui.  74:  1-47,  1907. 

12.  Chanute,  O.     The  preservation  of  railway  ties  in  Europe.     Trans.  A.mer.  8 

Civ.  Eng.,  1901,  p.  45. 

13.  Crawford,  Carl  G.     The  open  tank  method  for  the  treatment  of  timber.     Forest 

Service,  U.  S.  Dept.  Agr.,  Circ.  101:  1-15,  1907. 

14.  Brush  and  tank  pole  treatment.     Forest  Service,  U.  S.  Dept.  Agr.,  Circ.. 

104:  1-24,  1907. 

15.  Curtis,  W.  W.     The  artificial  preservation  of  railroad  ties  by  the  use  of  sine 

chloride.     Trans.  Amer.  Soc.  Civ.  Eng.,  p.  42,  1899. 

16.  Ellis,  J.  B.,  and  Galloway,  B.  T.     Jour.  Myc  ,  5:  141-142,  L899. 

17.  Emerson,  R.  A.     The  relation  of  early  maturity  to  hardiness  in  trees.     Nebr. 

Agr.  Expt.  Sta.,  Rept.  19:101-110,  figs.  1-13,  1906. 

18.  Felt,  E.  P.     Insects  injurious  to  maple  trees.     N.  Y.  Forest,  Fish,  and  Game 

Com.,  Rept.  4:367-395,  1898. 

19.  Insects  injurious  to  elm  trees.     N.  Y.  Forest,  Fish,  and  Game  Com., 

Rept.  5:351-379,  1899. 

20.  Insects  affecting   forest   trees.     N.  Y.   Forest,   Fish,  and   Game  Com., 

Rept.  7:479-534,  1903. 

21.  Insects  affecting  park  and  woodland  trees.     \.  Y.  Stan-  Mus    Memoir, 

8:1-877,  pis.  1-70,  1905-6. 

22.  Fitch,  Asa.     Report  on  the  noxious,  beneficial,  and  otto  £  the  £ 

New  York,  1:1-180,  1855;  2:1-336,  1856;  3:1-172,  L859;  5:1 

23.  Freeman,  E.  M.    Minnesota  plant  diseases,  pp.  235 

24.  Galloway,  B.  T.     U.  S.  Dept.  Agr.,  Rept.  for  188S,  pp.  32 

25.  Frosts  and   freezes  as  affecting  cultivated    plants,     i 

Yearbook  for  1895,  pp.  143-158,  1896. 

149  69 


70  DISEASES   OF    DECIDUOUS   FOREST   TREES. 

26  Galloway,  B.  T.     Progress  in  the  treatment  of  plant  diseases  in  the  United 

States.     U.  S.  Dept.  Agr.,  Yearbook  for  1899,  pp.  191-199,  1900. 

27    and  Woods,  A.  F.     Diseases  of  shade  and  ornamental  trees.     U.  S.  Dept. 

Agr.,  Yearbook  for  1896,  pp.  237-254,  1897. 

28.  Grinnell,  Henry.     Seasoning  of  telephone  and  telegraph  poles.     Forest  Serv- 

ice, U.  S.  Dept.  Agr.,  Circ.  103:1-16,  1907. 

29.  Prolonging  the  life  of  telephone  poles.     U.  S.  Dept.  Agr.,  Yearbook  for 

1905,  pp.  455-464,  1906. 

30.  Hartig,  PvObt.     Wichtige  Krankheiten  der  Waldbiiume,  pp.  1-127,  pis.  1-6,  1874. 
31    Die  durch  Pilze  erzeugten  Krankheiten  der  Waldbiiume,  pp.  1-24,  1875, 

2ded. 

32.  Die  Zersetzungserscheinungen  des  Holzes  der  Nabelholzbaume  und  der 

Eiche,  pp.  1-151,  pis.  1-21,  1878. 

33.  Der  iichte  Hausschwamm,  pp.  1-82,  pis.  1-2,  1885. 

34.  Lehrbuch  der  Pnanzenkrankheiten,  pp.  1-324,  1900,  3d  ed. 

35.  Text-book  of  the  diseases  of  trees.     Translated  by  William  Somerville 

and  H.  Marshall  Ward,  pp.  1-331,  1894. 

36.  Haselhoff,    E.,    and   Lindau,    G.     Die   Beschiidigung   der   Vegetation   durch 

Rauch,  pp.  1-412,  1903. 

37.  Haywood,  J.  K.     Injury  to  vegetation  by  smelter  fumes.     Bur.  Chem.,  U.  S. 

Dept.  Agr.,  Bui.  89:1-23,  pis.  1-6,  1905. 

38.  Heald,  F.  D.     A  disease  of  the  cottonwood  due  to  Elfvingia  megaloma.     Nebr. 

Agr.  Expt.  Sta.,  Rept.  19:92-100,  pis.  1-4,  1906. 

39.  Hedgcock,  G.  G.     Studies  upon  some  chromogenic  fungi  which  discolor  wood. 

Mo.  Bot.  Garden,  Rept.  17:59-114,  1906. 

40.  Hennings,  P.     Ueber  die  in  Gebauden  auftretenden  wichtigsten  holzbewohnen- 

den  Sch'wamme.     Hedwigia,  42: 178-191,  1903. 

41.  Ueber    die   an    Biiumen   wachsenden    heimischen    Agaricineen.     Hed- 
wigia, 42: (233)-(240),  1903. 

42.  Hopkins,  A.  D.     Bur.  Ent.,  U.  S.  Dept.  Agr.,  Buls.  21,  28,  32,  37,  48,  56,  58; 

Circs.  55,  61,  82,  83,  90;  also  U.  S.  Dept.  Agr.,  Yearbook  for  1902,  pp.  265-282; 
1903,  pp.  313-328;  1904,  pp.  381-398;  1905,  pp.  249-256. 

43.  Catalogue  of  West  Virginia  forest  and  shade  tree  insects.     W.  Va.  Agr. 

Expt.  Sta.,  Bui.  32:171-251,  1893. 

44.  Howard,  Albert.     Suggestions  for  the  removal  of  epiphytes  from  cacao  and  lime 

trees.     W.  Indian  Bui.  3:189-197,  1902. 

45.  Klebahn,  H.     Jahrb.  f.  Wiss.  Bot.,  41:485-560,  1905. 

46.  Lamson-Scribner,  F.     Leaf-spot  disease  of  catalpa.     U.  S.  Com.  Agr.,  Rept.  for 

1887,  pp.  364-366,  1888. 

47.  Lightfoot,  J.     Flora  Scotica,  2:1034,  1777. 

48.  Lindroth,  J.  I.     Beitrage  zur  Kentniss  der  Zersetzungserscheinungen  des  Bir- 

kenholzes.     Naturw.-Zeitschr.  f.  Land-  u.  Forstwiss.,  2:393-406,  1904. 

49.  Lintner,  J.  A.     Injurious  and  other  insects  of  the  State  of  New  York,  1:1-381, 

1882;  2:1-265,  1885;  3:83-154,  1887;  4:1-237,  1888;  5:147-347,  1889;  6:100-203, 
1890;  7:199-404,  1891;  8:105-320,  1893;  9:291-494,  1893;  10:341-633,  1895; 
11:89-324,  1896;  12:163-398,  1897;  13:331-390,  1898. 

50.  Lloyd,  C.  G.     Mycological  notes,  135:60,  1901. 

51.  MacMillan,  H.  R.     Private  letter  containing  considerable  information  concerning 

Fomes  igniarius  in  western  Canada. 

52.  Mayr,  H.     Ueber  den  Parasitismus  von  Nectria  cinnabarina.     Inaug.  Dissert.,  pp. 

1-20,  pi.  1,  1882. 

53.  Zwei  Parasiten  der  Birke,  Polyporus  betulinus,  Bull.,  und  Polyporus 

laevigatus,  Fries.     Bot.  Centbl.,  19:22-29,  51-57,  taf.  1-2,  1884. 

149 


BIBLIOGRAPHY.  71 

54.  Merkel,  H.  W.     A  deadly  fungus  on  the  American  chestnut.     X.  V.  Zool. 

Ann.  Rept.  10:97-103,  1906. 

55.  Metcalp,  Haven.     The  immunity  of  the  Japanese  chestnut  to  the  bark  <li 

Bur.  Plant  Industry,  "U.S.  Dept.  Agr.,  Bui.  121,  pt.  VI,  pp.  55  56,  I 

56.  Diseases  of  ornamental  trees.     U.  S.  Dept.  Agr.,  Yearbook  for  L907,  pp. 

483^94. 

57.  Murrill,  W.  A.     Shade  trees.     N.  Y.  (Cornell)  Agr.  Expt.Sta.,  Bui.  205:  73  L20, 

1902. 

58.  The  Polyporaceae  of  North  America.     Bui.  Torr.  Bot.  Club,  30:  L10   112, 

1903. 

59. The  Polyporaceae  of  North  America.     Bui.  Torr.  Bot.  Club,  30:  300  301, 

1903. 

60.  A  new  chestnut  disease.     Ton-yea,  6:  186-189*,  1906. 

61.  A  serious  chestnut  disease.    Jour.  N.  Y.  Bot.  Garden,  7:  I  l:i   153,  1906. 

62.  Further  remarks  on  a  serious  chestnut  disease.     Jour.  N.  Y.  Bot.  Garden, 

7:203-211,  1906. 

63.  Nelson,  Aven.     The  winter  killing  of  trees  and  shrubs.     Wyo.  Agr.  Expl 

Bui.  15:  213-222,  1893. 

64.  Nelson,  John  M.     Prolonging  the  life  of  mine  timbers.     Forest  Service,  U.  S. 

Dept.  Agr.,  Circ.  Ill:  1-22,  1907. 

65.  Norton,  J.  B.  S.     Some  diseases  of  the  chestnut.     Md.  State  Hort.  Soc.,  Rept.  4: 

104-105,  1902. 

66.  Packard,  A.  S.     Insects  injurious  to  forest  and  shade  trees.     U.  S.  Ent.  Com., 

Bui.  7:  1-275,  1881. 

67.  Insects  injurious  to  forest  and  shade  trees.     I'.  S.  Km.  Com.,  Rept.  5: 

1-945,  1890. 

68.  Peirce,  C.  J.     On  the  mode  of  dissemination  and  on  the  reticulations  of  Ramalina 

reticulata.     Bot.  Gaz.,  25:  404-417,  1898. 

69.  Pollock  J.  B.     A  canker  of  the  yellow  birch  and  a  Nectria  associated  with  it. 

Mich.  Acad.  Sci.,  Rept.  7:  55-56,  1905. 

70.  Rehm,  II .     Ann.  Myc,  5:  210,  1907. 

71.  Sandsten,  E.  P.     The  influence  of  gases  and  vapors  upon  the  growth  <>i"  plants. 

Minn.  Bot.  Studies,  2:  53-68,  1898. 

72.  Sargent,  C.  S.     Manual  of  the  trees  of  North  America,  pp.  L-826,  !!><»">. 

73.  Schrenk,  H.  von.     Parasitism  of  Epiphegus  virginiana.     Proc.  Amer.  Mi.  : 

15:  91-128,  1894. 

74.  The  trees  of  St.  Louis  as  influenced  by  the  tornado  <>t   1896.     Trans.  Acad. 

Sci.  St.  Louis,  8:  25-41,  pis.  3-9,  1898. 

75.  On  the  mode  of  dissemination  of  Usnea  barbata.     Trans.  A.cad.  Sci.  St. 

Louis,  8:  189-198,  pi.  16,  1898. 

76.  A  sclerotioid  disease  of  beech  root.     Mo.  Bot.  Garden,  Rept.  10:61-70, 

pis.  55-56,  1899. 

77.  -       -  Notes  on  Arceuthobium  pusillum.     Rhodora,  2:2  5,  pi.  12,  1900. 

78.  Fungous  diseases  of  forest  trees.     U.  S.  Depl  Agr.,  Yearbook  tar  L900,  pp. 

199-210,  1901. 

79.  Factors  which  cause  the  decay  of  wood.     Jour.    \V< 

6:  89-103,  pis.  1-3,  1901. 

80.  A  disease  of  the  black  locust  (Robinia  pseud 

Rept.  12:  21-31,  pis.  1-3,  1901. 

81.  The  decay  of  timber  and  methods  of  proveni  in-  it      Bur.  Plant  Indu 

IT.  S.  Dept.  Agr.,  Bui.  14:  1-96,  pis.  1-18,  1902. 

82. A  root  rot  of  apple  trees  caused  by  Thelephora  galacti 

34:  65,  1902. 
149 


72  DISEASES   OF    DECIDUOUS   FOREST    TREES. 

83.  Schrenk,  H.  von.     Diseases  of  the  hardy  catalpa.     Bur.  Forestry,  U.  S.  Dept. 

Agr.,  Bui.  37:  49-58,  pis.  20-30,  1902. 
84    A  disease  of  the  white  ash  caused  by  Polyporus  fraxinophilus.      Bur. 

Plant  Industry,  U.  S.  Dept,  Agr.,  Bui.  32:  1-20,  pis.  1-5,  1903. 

85.  Recent  progress  in  timber  preservation.     U.  S.  Dept.  Agr.,  Yearbook 

for  1903,  pp.  427-440,  1904.     Reprinted  in  Ind.  State  Board  of  Forestry  Rept. 
4:  64-78,  1904. 

86.  Report  on  the  condition  of  treated  timbers  laid  in  Texas,  February,  1902. 

Bur.  Forestry,  U.  S.  Dept.  Agr.,  Bui.  51:  13-37,  1904. 

87.  Constriction  of  twigs  by  the  bag  worm  and  incident  evidence  of  growth 

pressure.     Mo.  Bot.  Garden,  Rept.  17:  153-181,  pis.  20-26,  1906. 

88.  On  frost  injuries  to  sycamore  buds.     Mo.  Bot.  Garden,  Rept.  18:  81-83, 

pi.  7,  1907. 

89.  Branch  cankers  of  Rhododendron.     Mo.  Bot,  Garden,  Rept.  18:  77-80, 

pis.  5-6,  1907. 

90. Sap-rot  and  other  diseases  of  the  red  gum.     Bur.  Plant  Industry,  U.S. 

Dept.  Agr.,  Bui.  114:  1-34,  pis.  1-8,  1907. 

91.  and  Hill,  Reynolds.     Seasoning  of  timber.     Bur.  Forestry,  U.  S.  Dept. 

Agr.,  Bui.  41:  1-48,  pis.  1-18,  1903. 

92.  Schuman,  K.,  and  Latjterbach,  K.     Die  Flora  der  deutschen  Schutzgebiete  in 

der  Siidsee,  p.  42,  1901. 

93.  Simpson,  J.  M.     Osier  culture.     Bur.  Forestry,  U.S.  Dept.  Agr.,  Bui.  19:  18-20, 

1898. 

94.  Spaulding,  Perley.    A  disease  of  black  oaks  caused  by  Polyporus  obtusus,  Berk. 

Mo.  Bot.  Garden,  Rept.  16:  109-116,  pis.  13-19,  1905. 

95.  Heart  rot  of  Sassafras  sassafras  caused  by  Fomes  ribis.     Science,  n.  s., 

26:  479-480,  1907. 

96.  Stone,  G.  E.     Injuries  to  shade  trees  from  electricity       Mass.  (Hatch)  Agr.  Expt. 

Sta.,  Bui.  91:  1-21,  1903. 

97.  Mass.  (Hatch)  Agr.  Expt.  Sta.,  Rept,  19:  180-185,  1907. 

98.  Sud worth,  G.  B.     Nomenclature  of  the  arborescent  flora  of  the  United  States. 

Div.  Forestry,  U.  S.  Dept.  Agr.,  Bui.  14:  1-419,  1897. 

99.  Check  list  of  the  forest  trees  of  the  United  States.     Div.  Forestry,  U.S. 

Dept.  Agr.,  Bui.  17:  1-144,  1898. 

100.  Trelease,  William.     Harriman  Alaska  Expedition,  cryptogamic  botany,  5: 1-54, 

pis.  2-7,  1904. 

101.  Tubeuf,  Carl  von.     Beitrage  zur  Kenntniss  der  Baumkrankheiten,  pp.  1-61, 

pis.  1-5,  1888. 

102.  ■ Diseases  of  plants  induced  by  cryptogamic   parasites.     Translated  by 

Wm.  G.  Smith,  pp.  1-598,  1897. 

103.  Tuzson,  J.     Anatomische  und  mykologische  Untersuchungen  uber  die  Zerset- 

zung  und  Conservierung  des  Rothbuchenholzes.     Math.  u.  Naturwiss.  Ber.  aus 
Ungarn.,  19:  242-282,  1903. 

104.  Waite,  M.  B.     Experiments  with  fungicides  in  the  removal  of  lichens  from  pear 

trees.     Jour.  Myc,  7:  264-268,  pis.  30-31, 1893. 

105.  Waugh,  F.  A.     Lichens  on  fruit  trees.     Meehan's  Monthly,  8:  173,  fig.  1, 1898. 
106. •    Lichens  on  plum  trees.     Vt.  Agr.  Expt.  Sta.  Rept.,  pp.  289-290,  1898. 

107.  Webber,  H.  J.     The  two  freezes  of  1894-95  in  Florida,  and  what  they  teach. 

U.  S.  Dept,  Agr.,  Yearbook  for  1895,  pp.  159-174,  1896. 

108.  Weiss,  H.  F.     The  preservative  treatment  of  fence  posts.     Forest  Service,  U.  S. 

Dept.  Agr.,  Circ.  117:  1-15,  1907. 

109.  Widtsoe,  Jno.  A.     The  relation  of  smelter  smoke  to  Utah  agriculture.     Utah 

Agr.  Expt.  Sta.,  Bui.  88: 147-179,  1903. 
149 


BIBLIOGRAPHY.  73 

110.  Wiegand,  K.  M.     Some  studies  regarding  the  biology  of  buds  and  twigs  in  winter 

Bot.  Gaz.,  41:  373-424,  1906. 

111.  The  occurrence  of  ice  in  plant  tissues.     Planl  World,  9:  2  i  5 

1906.     (Contains  a  very  full  bibliography  of  this  subject .  I 

112.  Wieler,  A.     Untersuchungen  fiber  die  Einwirkung  schwefliger  Saure  auf  die 

Pflanzen,  pp.  1-427,  1905. 

113.  Wilcox,  E.  Mead.     A  rhizomorphic  root  rot  of  fruit  trees      Pkla    \-    i 

Bui.  49:  1-32,  pis.  1-11,1901. 

114.  A  leaf-curl  disease  of  oaks.     Ala.  Agr.  Expt.  Sta.,  Bui.  L26:  171    L87   L903 

149 


PLATES. 


149  75 


DESCRIPTION  OF  PLATES. 

Plate  I  Frontispiece.  A  tree  of  aspen  (Populus  tremuloides)  bearing  several  sporo- 
"  phores  of  Fomes  igniarius.  The  tree  is  badly  rotted  within,  and  the  fungus  has 
formed  its  fruiting  bodies  at  old  knot  holes  left  by  the  dying  of  small  lateral 
branches.     The  tree  is  still  alive,  but  is  sure  to  die  within  a  few  years. 

Plate  II.  Effect  of  Fomes  igniarius  upon  living  trees.  Fig.  1.— Cross  section  of  the 
trunk  of  a  tree  of  silver  maple  (Acer  saccharinum)  which  bore  but  one  fruiting 
body,  this  being  the  only  external  indication  of  disease.  Note  the  black,  narrow 
zones'  surrounding  the  completely  decayed  wood;  also  the  place  of  entrance  at 
the  upper  right-hand  corner  produced  by  the  rotting  of  a  dead  lateral  branch. 
Fig.  2.— Cross  section  of  a  living  tree  of  aspen  badly  diseased  with  the  white 
heart-rot.     Note  concentric,  dark  zones  surrounding  the  diseased  part. 

Plate  III.  Decay  of  living  trees  caused  by  wound  fungi.  Fig.  1.— Cross  section  of 
a  living  tree  of  beech  (Fagus  atropunicea)  decayed  by  Fomes  igniarius.  This 
tree  bore  but  a  single  fruiting  body,  this  being  the  only  external  indication  of 
disease.  The  decay  extended  about  4  feet  both  upward  and  downward  from 
the  sporophore.  Fig.  2.— Cross  section  of  the  trunk  of  a  living  red  oak  (Quercus 
rubra)  rotted  by  Fomes  everhartii. 

Plate  IV.  Polyporus  sulphureus.  Fig.  1.— A  large  compound  fruiting  body  of 
Polyporus  sulphureus,  such  as  is  very  often  found.  Fig.  2.— Cross  section  of  the 
trunk  of  a  living  tree  of  post  oak  (Quercus  minor)  rotted  by  Polyporus  sulphureus. 

Plate  V.  Piped-rot.  Fig.  1.— Longitudinal  section  of  the  trunk  of  a  living  tree  of 
black  jack  oak  showing  the  piped-rot.  Fig.  2.— A  piece  of  chestnut  wood  dis- 
eased with  the  piped-rot. 

Plate  VI.  Fomes  nigricans.  Fig.  1.— Cross  section  of  the  trunk  of  a  living  tree  of 
paper  birch  (Betula  papyri/era)  diseased  by  Fomes  nigricans.  Fig.  2.— The  trunk 
of  a  paper  birch  (Betula  papyri/era)  showing  an  irregular  aborted  sporophore  of 
Fomes  nigricans  growing  at  an  old  wound. 

Plate  VII.  Hydnum  erinaceus.  Fig.  1.— Cross  section  of  the  trunk  of  a  living  tree 
of  white  oak  (Quercus  alba)  with  the  heartwood  rotted  by  this  fungus.  Note  below, 
at  the  left,  two  burrows  of  the  oak  borer  through  which  this  fungus  probably 
entered.  Fig.  2.— Fruiting  body  of  Hydnum  erinaceus  growing  in  a  hollow  oak 
trunk. 

Plate  YIII.  Fomes  fomentarius.  Fig.  1.— Sporophores  growing  upon  a  dead  tree  of 
beech  (Fagus  atropunicea).  Fig.  2.— Cross  section  of  the  trunk  of  a  dead  beech 
tree  with  the  sap  wood  rotted  by  this  fungus;  the  heartwood  is  practically  sound. 

Plate  IX.  Polyporus  betulinus.  Fig.  1.— A  dead  trunk  of  yellow  birch  (Betula  lutea) 
with  a  large  sporophore  of  Polyporus  betulinus.  This  fruiting  body  measured 
about  1  foot  in  diameter.  Fig.  2.— Cross  section  of  the  trunk  of  a  dead  yellow 
birch  tree  with  a  fruiting  body  of  Polyporus  betulinus.  The  wood  is  entirely 
rotted. 

Plate  X.  Daedalea  quercina.  Fig.  1.— An  oak  railroad  tie  with  fruiting  bodies  of 
Daedalea  quercina.  The  tie  is  badly  decayed  within.  Fig.  2.— A  section  of  the 
above  tie  2  feet  from  the  end  bearing  the  fruiting  bodies  of  the  fungus.  It  will 
be  noted  that  in  the  lower  part  it  is  quite  seriously  affected. 

149 
76 


Bu  .  149,  Bureau  of  Plant  Industry,  U.  S.  Dept.  of  A^ricultur 


Plate  II. 


Fig.  1—  Cross  Section  of  the  Trunk  of  a  Living  Silver  Maple  Rotted  by 

fomes  igniarius. 


Fig.  2.— Cross  Section  of  a  Living  Aspen  Tree  Rotted  by  Fomes 


Bui.  149,  Bureau  of  Plant  Industry,  U.  S.  Dept.  of  Agriculture. 


P-ATE      !||, 


MJi 


Fig.  1.— Cross  Section  of  a  Living  Beech  Tree  Diseased  by 
fomes  igniarius. 


Fig.  2.— Cross  Section  of  a  Living  Red  Oak  Tree  Rotted  i 
Fomes  EVERHARTII. 


149,  Bureau  of  Plant  Industry,  U.  S.  Dept.  of  Agricul 


Plate     v 


Fig.  1.— Fruiting  Body  of  Polyporus  sulphureus 


Fig.  2.— Cross  Section  of  a  Living  Post  Oak  Tree  Rotted  by  Polypo 

sulphureus. 


Bui.  149.  Bureau  of  Plant  Industry,  U.  S.  Dept.  of  Agncultur 


Plate  v 


wmm 


Fig.  1—  Piped-rot  of  Oak. 


' 


Fig.  2.— Piped-rot  of  Chestnut. 


Bui.  149,  Bureau  of  Plant  Industry,  U.  S.  D 


y,  U.  S.  Dept.  of  Agriculture. 


Plate  VI. 


2   O 


Jul.   149,  Bureau  of   Plant  Industry,  U.  S.  Dept.  of  Agricultur 


P^A^E    V! 


' 


f  "s^ji 


J^Mm  SIN  -; 


"/fc-J 


■  ! 


y 


Fig.  1.— Cross  Section  of  a  Living  White  Oak  Tree  Decayed  by  Hydnum  erinace 


US. 


Fig.  2.— Fruiting  Body  of  Hydnum  erinaceus  in  a  Hollow  Log 


149,  Bureau  of  Plant  Industry,  U.  S.  Dept.  of  Agricultur 


Plate  Vlll. 


iff 


o  H 

2    33 

m  m 
z  m 

2* 


I 


r> 


Bui.   149,   Bureau  of  Plant  Industry,  U.  S.  Dept.  of  Agricultur 


Plate  IX. 


Fig.  1.— A  Dead  Yellow  Birch  Tree  with  Fruiting  Body  of  Polyporus  betulinus. 


i  ._:v,  ■ 


Fig.  2-Cross  Section  of  Yellow  Birch  Tree  Rotted  by  Poi 


Bui.  149,  Bureau  of  PI 


in+  Industry,  U.  S.  Dept.  of  Agricultur 


Plate  X. 


Fig.  1.— An  Oak  Railroad  Tie  Rotted  by  Daed> 


LEA  QUERCINA. 


Fig.  2.— Cross  Section  of  the  Tie  Shown  in  Figure  1.  Two  Fs 

Fruiting  Body. 


INDEX 


Acer  spp.    See  Maple. 

Acid,  sulphuric,  production  commercially  from  smelter  e  si  ion  .10-11 

Aesculus  hippocastanum.     See  Chestnut,  horse. 

Alder,  red  heart-rot,  susceptibility 

white  heart-rot,  susceptibility \ 

Alnus  incana.     See  Alder. 

Animals,  injuries  to  trees j  } 

Apple,  slime-flux  injury • . } 

red  heart-rot,  susceptibility 

white  heart-rot,  susceptibility 

Arceuthobium  spp.,  description,  propagation,  and  method  of  control [6   17 

Ash,  leaf-rusts  caused  by  fungi I<i 

mistletoe  injury I .-, 

white  heart-rot,  cause,  description,  and  prevention \w   \~ 

rot,  susceptibility 1<» 

Aspen,  heart-rot,  susceptibility 

white  heart-rot,  susceptibility 20,  27,  28,  30, 31, 32 

Atkinson,  G.  F.,  reference  to  work 

Bacteria,  soil,  conditions  affecting I .; 

Balm  of  Gilead,  white  heart-rot,  susceptibility 

Bark  disease,  chestnut,  cause,  ravages,  and  characteristics 

Beech,  injury  by  Fomes  fomentarius 50  51, 74 

Nummularia  fungi 22 

sulphur  gas  and  excessive  ground  water LI,  13 

sap-rot,  occurrence 57 

timber,  rapid  decay »;:*, 

white  heart-rot,  susceptibility 26, 27, 28 

rot,  susceptibility 

Betula  spp.    See  Birch. 

Bibliography,  forest  tree  diseases 

Birch,  heart-rot,  susceptibility , 

injury  byFomes  fomentarius 

leaf-rust  fungus 

red  heart-rot,  cause  and  description 

sap-rot,  cause  and  description 51   52,  7 ! 

caused  by  Polystictus  pergamenus,  occurrence 

white-rot,  susceptibility 

yellow,  slime-flux  injury 

white  heart-rot,  susceptibility 

Black  gum.     See  Gum,  black. 

jack,  susceptibility  to  sulphur-gas  injury 

Blight,  leaf  and  twig,  sycamore,  description,  effects,  and  control.... 

Bordeaux  mixture,  control  of  mildews 

Borers,  locust,  preceding  fungous  growl  hs 

oak,  preceding  fungous  growths 

Broadleaf  poles,  posts,  trees.    See  Poles,  Posts,  Tre 

149  7: 


78  DISEASES    OF    DECIDUOUS    FOREST    TREES. 

Page. 

Buckhout,  W.  A. ,  reference  to  work 10 

Butternut,  red  heart-rot,  susceptibility 37 

white  heart-rot,  susceptibility 27,  32, 33 

Castanea  dentata.     See  Chestnut. 

crenata.    See  Chestnut,  Japanese. 

Catalpa,  soft  heart-rot,  cause,  description,  and  prevention 47-48 

speciosa.    See  Catalpa. 

Cenangium  spp.,  cause  of  oak  disease 22 

Checks,  timber,  entrance  of  sap-rotting  fungi 54,  55,  65 

Chemicals,  treatment  of  wood  to  prevent  decay 66,  67 

Cherry,  black,  sap-rot,  occurrence 57 

Chestnut,  bark  disease,  cause,  ravages,  and  characteristics 22 

immune  varieties 22 

horse,  white-rot,  susceptibility 49 

Japanese,  resistance  to  bark  disease 22 

oak.     See  Oak,  chestnut. 

piped-rot,  description,  growth,  and  prevention 39-40 

red  heart-rot,  susceptibility 37 

sap-rot,  occurrence 57 

susceptibility  to  sulphur-gas  injury 11, 12 

timber,  decay  caused  by  Daedalea  quercina 61 

rapidity 63 

Clitocybe  parasitica.     See  Mushroom,  honey. 

Coal-tar  creosote  for  painting  tree  wounds 36,  37 

Coke  ovens,  injuries  to  trees 10 

Cold ,  effects  on  forest  trees 13-14 

Conifers,  susceptibility  to  sulphur-gas  injury 11-12 

Copper  smelter  fumes,  injuries  to  trees 10-12 

Coppice  growth,  painting  cut  surfaces  of  stumps 37,  40 

Coral  fungus  causing  white-rot,  description,  growth,  and  results 44-45 

Cornus  florida.     See  Dogwood. 

Cottonwood,  mistletoe  injury 15 

sap-rot  caused  by  Fomes  applanatus,  description 58-60 

Creosote,  coal-tar,  painting  tree  wounds 36,  37 

Cyllene  robiniae,  locust  borer  preceding  the  fungus  Fomes  rimosus 45 

Daedalea  quercina,  cause  of  sap-rot,  distribution,  description,  and  timber  de- 
struction    61,  74 

Decay,  timber,  caused  by  Stereum  frustulosum 60-61 

.  causes,  rate,  prevention,  etc 62-67 

preventive  methods 66-67 

rate,  different  woods 56,  58 

Decays  caused  by  wound  fungi 49-52 

Diseases  caused  by  insects 14 

miscellaneous  fungi ' 18-25 

parasitic  and  saprophytic  organisms 14-25 

sulphur  gases  and  smoke 10-12 

wound  fungi 25-52 

environmental 10-14 

tree,  classification 9 

Dogwood,  slime-flux  injury 24 

Dry-rot,  danger  in  structural  timbers <>7 

Elfvingia  megaloma,  synonym  of  Fomes  applanatus 58 

140 


INDEX.  79 

Elm,  mildew  injury [g 

mistletoe  injury I ;( 

slime-flux  injury _•  1 

white-rot,  susceptibility Is 

Environment,  influence  on  prevalence  of  while  heart-rol 

Europe,  investigations  of  effects  of  sulphur  fumes  on  vegetation 10.  1 1.  12 

Fagus  spp.    See  Beech. 

False-tinder  fungus.     See  Fomes  igniarius. 

Fence  posts,  decay  caused  by  Polystictus  versicolor 

Flux,  slime,  diseases,  description 

Fomes  applanatus,  cause  of  sap-rot  of  cottonwood v 

habits 

everhartii,  cause  of  heart-rot  of  oak,  description  and  sporophores 18,74 

fomentarius,  description  and  injury  to  trees 50-51, 74 

fraxinophilus,  cause  of  white  heart-rot  of  ash,  description,  etc 16-47 

sporophores,  description It; 

fulvus,  cause  of  red  heart-rot  of  birch,  description 17 

destruction  of  olive  trees  in  Italy 17 

igniarius,  distribution,  description,  growth,  and  prevention 27-37,  7  1 

effect  on  wood  structure : I  1  35 

fungus  causing  white  heart -rot 25  37 

sporophores,  formation 

synonymy 

nigricans,  description,  growth  habits,  and  injuries  to  tree- 42-44 

sporophores,  description  and  growth 

rimosus,  cause  of  black  locust  disease,  description  and  growth 15   W 

sporophores,  growth  and  appearance 45   16 

Forest  trees.     See  Trees,  forest. 
Fraxinus  spp.     See  Ash. 

Freeman,  E.  M.,  reference  to  work 19 

Fruit  trees.     See  Trees,  fruit. 

Fungi,  beneficial,  development,  effect  of  soil  conditions 

causing  leaf  diseases Is  -  • 

sap-rot  through  tree  wounds,  description 

disease-bearing,  classification 

growing  on  dead  wood 31,38,  12, 

leaf-blister,  injuries  to  trees 

miscellaneous,  causing  diseases  of  trees 

root-rotting,  description  and  effects 

sap-rotting,  resembling  Polystictus  versicolor  and  P.  pergami 

saprophytic 

cause  of  decay  in  structural  I  imber 

soil,  development,  effect  of  soil  conditions 

wound,  causing  diseases  of  forest  trees 

Fungus,  coral,  causing  white-rot,  description,  growth,  etc 

false-tinder.     See  Fomes  igniarius. 

micorrhizal,  development,  effect  of  soil  conditions 

tinder,  description  and  injury  to  trees 

transmission  from  oaks  to  fruit  trees 

Gas  condensation  a  preventive  of  injury  to  vegetal  ion 

injury,  preventive  methods 

Gases,  sulphur,  injuries  to  trees 

Gloeosporium  nervisequum,  cause  of  sycamore  leaf-blig]  I 
7Q1F.9 pini   i4Q — on a 


80  DISEASES   OF   DECIDUOUS   FOREST   TREESo 

Page. 

Gnomonia  venata,  cause  of  sycamore  leaf-blight 20 

Gum,  black,  mistletoe  injury 15 

susceptibility  to  sulphur-gas  injury 11, 12 

red,  mistletoe  injury 15 

sap-rot,  occurrence 57 

southern  moss  injury 17 

tolerance  of  ground  water  in  soils 13 

"Hallimasch,"  root-rotting  fungus,  description,  method  of  growth,  and  effects 

on  trees 23-24 

Hartig,  Robert,  references  to  work 30,  49 

Haselhoff,  E.,  and  G.  Lindau,  reference  to  work 11 

Haywood,  J.  K.,  reference  to  work 10 

Heald,  F.  D.,  references  to  work  and  quotation 58,  59 

Heart-rot.    See  Rot,  heart. 

Heartwood,  resistance  to  decay  in  different  species 56 

Hemlock,  susceptibility  to  sulphur-gas  injury 11, 12 

Hickory,  sap-rot,  occurrence 57 

susceptibility  to  sulphur-gas  injury 11, 12 

white  heart-rot,  susceptibility 26 

Hicoria.     See  Hickory. 

pecan.     See  Pecan. 
Honey  mushroom.     See  Mushroom,  honey. 

Hosts,  different,  susceptibility  to  white  heart-rot 26-27 

Hydnum  erinaceus,  cause  of  white-rot,  description,  growth,  and  results 44^5,  74 

Insects  causing  diseases  of  trees 14 

Introduction  to  bulletin 9 

Juglans  cinerea.     See  Butternut. 

nigra.     See  Walnut,  black. 

Leaf-blight,  sycamore,  description,  effects,  and  control  measures 20 

blister  fungi,  injury  to  oak  trees 21 

discoloration,  caused  by  sulphur  fumes,  list  of  susceptible  trees 11-12 

diseases  caused  by  different  fungi 18-21 

control  by  burning  dead  leaves 19,  20,  21 

spots  of  forest  trees  caused  by  fungi 20-21 

Lichens,  injury  to  forest  trees 18 

Lightfoot,  J.,  statement  as  to  uses  of  fungus  Fomes  igniarius 28 

Linden,  white-rot,  susceptibility 48 

Lindroth,  J.  I.,  studies  on  heart-rot,  references  to  work 42,  43 

Liquidambar  styraciflua.     See  Gum,  red. 
Liriodendron  tulipifera.     See  Poplar,  tulip. 
Live  oak.     See  Oak,  live. 

Locust,  black,  disease  caused  by  Fomes  rimosus,  description 45-46 

red  heart-rot,  susceptibility 37 

Maple,  leaf-spot,  description  and  control -' 20 

silver,  mildew  injury ^ 

Maples,  red  heart-rot,  susceptibility 37 

sap-rot,  occurrence - 57 

slime-flux  injury 24 

susceptibility  to  sulphur-gas  injury 11, 12 

tar-spot  disease,  cause,  description,  and  control 19 

white  heart-rot,  susceptibility 23,  27.  31,  33,  74 

rot,  susceptibility 

Mayr,  IL,  references  to  work 49,  52 

149 


INDEX.  81 

Melampsora  spp.,  cause  of  leaf-rusts  on  poplar,  hitch,  and  willow 19 

Mesquite,  mistletoe  injury 1  - 

Mildews,  Erysipheae,  description  and  control 1  > 

Mistletoe,  injuries  to  forest  trees 1 1   | ; 

Mosses,  injuries  to  forest  trees 17 

Mushroom,  honey,  description,  growth,  habits,  and  injuries  to  trees 

fruiting  bodies,  development 

method  of  infection 

Nectria  cinnabarina,  injury  to  forest  trees  and  mode  ,,i' aitink 21   22 

Nummularia  fungi,  injury  to  forest  trees  and  mode  of  attack 23 

Nyssa  sylvatica.     See  Gum,  black. 

Oak,  black,  susceptibility  to  sulphur-gas  injury ? I  _< 

chestnut,  susceptibility  to  sulphur-gas  injury -.  .    U,  12 

' ' hill "  and  ' ' bottom, ' '  comparative  resistance  to  decay 

live,  southern  moss  injury I ; 

piped-rot,  description,  growth,  and  prevention 

post,  susceptibility  to  sulphur-gas  injury 1 1 .  I  l( 

red,  decay  of  timber,  rapidity 63 

mildew  injury 1  > 

scarlet,  susceptibility  to  sulphur-gas  injury 11.  I  _' 

Spanish,  disease  similar  to  chestnut  bark  disease L'l' 

susceptibility  to  sulphur-gas  injury 1 1 .  1 1 

timber,  decay  caused  by  Daedalea  quercina,  description 61,74 

Stereum  frustulosum 60  61 

white-rot,  susceptibility 

susceptibility  to  sulphur-gas  injury 11, 12 

Oaks,  heart-rot  caused  by  Fomes  everhartii,  description I B 

injury  by  Thelephora  galactina 24 

Nummularia  fungi 22 

leaf-blister  fungi  injury 21 

mistletoe  injury 

red  heart-rot,  susceptibility 37, 74 

sap-rot,  occurrence 57 

soft-rot  caused  by  Polyporus  obtusus,  description,  etc 41  42 

tolerance  of  ground  water  in  soils 

white  heart-rot,  susceptibility 

rot,  cause,  description,  growth,  and  results 11  45,  7 1 

Olive  trees,  destruction  by  Fomes  fulvus  in  Italy 

Parasites  causing  diseases  of  trees 

Pear,  red  heart-rot,  susceptibility 

white-rot,  susceptibility 

Pecan,  southern  moss  injury 

Phoradendron  navescens,  injuries  to  forest  trees,  propagation,  and  efforts 

control : 

Phyllosticta  acericola,  cause  of  maple  leaf-spot 

Piling  timber,  precautions 

Pine,  pitch,  susceptibility  to  sulphur-gas  injury 


scrub,  susceptibility  to  sulphur-gas  in] 


urv 


11 

white,  susceptibility  to  sulphur-gas  injury ' '  •  '  - 

Pinus  spp.     See  Pine. 
Piped-rot.     See  Rot,  piped. 
Pitch  pine.    See  Pine,  pitch. 

149 


82  DISEASES   OF  DECIDUOUS   FOREST   TREES. 

Page. 

Plants,  epiphytic,  injuries  to  trees 17 

parasitic,  causing  diseases  of  trees 14-18 

Platanus  occidentalis.    See  Sycamore. 

Plates,  description 74 

Poles,  broadleaf,  decay  caused  by  Polystictus  versicolor,  description 53-56 

Polyporus  betulinus,  cause  of  birch  sap-rot,  description 51-52 

sporophores,  description 51,  74 

obtusus,  cause  of  oak  soft-rot,  description 41-42 

sporophores,  characteristics 41 

squamosus,  cause  of  white-rot,  description 48-49 

sulphureus,  description,  growth,  habits,  and  injury  to  trees 37-39,  74 

edible  qualities 37 

preventive  measures 38-39 

Polystictus  pergamenus,  cause  of  sap-rot  in  dead  wood,  description 56-58 

decay  similar  to  that  caused  by  Polystictus  versicolor . .        58 

species,  resembling  P.  versicolor  and  P.  pergamenus 61 

versicolor,  cause  of  sap-rot  in  dead  wood,  progress  of  decay 53-56 

soft  heart-rot  of  catalpa,  description,    growth, 

and  prevention 47-48 

distribution 53 

sporophores,  description  and  growth  in  cut  timber 53-56 

Poplar,  leaf-rust  fungus  injury 19 

tulip,  sap-rot,  occurrence 57 

susceptibility  to  injury  by  sulphur  gas  and  ground  water 11, 12, 13 

white  heart-rot,  susceptibility 30 

Populus  balsamifera.     See  Balm  of  Gilead. 
deltoides.    See  Cottonwood, 
tremuloides.     See  Aspen. 
Post  oak.     See  Oak,  post. 

Posts,  broadleaf,  decay  caused  by  Polystictus  versicolor,  description 53-56 

Preservation,  wood,  by  chemicals  to  prevent  decay 66,  67 

Prionoxystus  robiniae,  oak-boring  insect  preceding  fungus  of  soft*-rot 41 

Prosopis  juliflora.     See  Mesquite. 

Puccinia  fraxinata,  cause  of  leaf-rust  of  ash 19 

Punks,  fungi  injurious  to  forest  trees,  description 25-61 

Pyrenomycetes  fungi,  injury  to  forest  trees,  mode  of  attack 21 

Pyrus  communis.     See  Pear. 

malus.     See  Apple. 
Quercus  spp.     See  Oak. 

Ramalina  reticulata,  injury  to  trees 18 

Red  gum.     See  Gum,  red. 

heart-rot.     See  Rot,  heart,  red. 

Rhizomorphs,  honey  mushroom,  description  and  growth 23-24 

Rhytisma  acerinum,  cause  of  tar-spot  disease  of  maple * 19 

Robinia  pseudacacia.    See  Locust. 

Root-rots,  causes,  symptoms,  and  destruction  of  trees 22-24 

Roots,  tree,  injury  by  gas  through  poisoned  soil 12 

Rot,  heart,  cause,  description,  and  injury  to  trees 42-44 

oaks,  caused  by  Fomes  everhartii,  description 48 

red,  birch,  cause  and  description 47 

caused  by  Polyporus  sulphureus 37-39 

soft,  catalpa,  cause,  description,  and  prevention 47-48 

140 


INDEX. 

p  _ 

Rot,  heart,  white,  ages  of  trees  liable  to  infect  ion 

ash,  cause,  description,  and  prevention n,   17 

cause  and  nature,  characteristic  signs 25  26 

fungus,  distribution 

effect  on  wood  structure ;  l  :>- 

hoste,  susceptibility  of  different  trees 26  27 

•     influence  of  environment,  factors  favorable  to  development. 

method  of  infection  and  spread 

prevalence,  influence  of  environment :;  I   33 

preventive  measures 

ultimate  fate  of  diseased  trees 

piped,  oak  and  chestnut,  description  and  growth  of  disease 

sap,  birch,  caused  by  Polyporus  betulinus,  description -  5]   ;,-_> 

caused  by  Daedalea  quercina,  description g] 

Fomes  applanatus,  description 

Polystictus  pergamenus,  description 

versicolor,  description 

Cottonwood,  cause  and  description  of  decay 

fungi  causing,  description 49  g] 

soft,  oaks,  cause,  description,  and  growth II    |_> 

white,  cause,  trees  affected,  and  description  of  fungus Is  49 

caused  by  Hydnum  crinaceus,  description 1 1    15 

Polyporus  squamosus,  description :  - 

Rots,  root,  causes,  symptoms,  and  destruction  of  trees 22  24 

sap,  caused  by  wound  fungi,  description 

species  of  deciduous  trees 

Rusts,  forest  trees,  description  and  control 19-20 

Salix  spp.    See  Willow. 
Sap-rot.    See  Rot,  sap. 

Saplings,  forest  trees,  susceptibility  to  sulphur-gas  injury 11 

Saprophytes  causing  diseases  of  trees 11  25 

Scarlet  oak.    See  Oak,  scarlet. 

Schuman,  K.,  and  K.  Lauterbach,  reference  to  work 

Scrub  pine.     See  Pine,  scrub. 

Season  checks  in  timber,  entrance  of  sap-rotting  fungi M. 

Shelf  fungi,  description  and  injuries  to  trees 

Slime-flux  diseases,  description l 

Smelters,  injuries  to  trees  from  fumes 1 1  >   12 

Smoke,  injuries  to  trees K 

Soil,  conditions  producing  disease ! 

injuries  by  gas  and  smoke 12 

Spanish  oak.     See  Oak,  Spanish. 

Spartina  cynosuroides,  occurrence  of  Fraximus  lanceolate 

Sporophores  of  Daedalea  quercina,  description I 

Fomes  fomentarius,  description 

igniarius,  formation 

Polyporus  betulinus,  description 

obtusus,  characterist  Lcs 

Polystictus  pergamenus,  description 

versicolor,  growth  and  description 

Spots,  leaf,  forest  trees,  caused  by  fungi 

Stag-headed  condition,  causes  in  soil  conditions 

149 


84  DISEASES    OF   DECIDUOUS   FOREST    TREES. 

Page. 

Stereum  frustulosum,  cause  of  decay  of  timbers,  description 60-61 

Sulphur  gases.     See  Gases,  sulphur. 

polyporus.     See  Polyporus  sulphureus. 

powdered,  for  control  of  mildews 18 

trioxid,  injuries  to  trees  near  copper  smelters 10 

Sulphuric  acid.     See  Acid,  sulphuric. 

Sycamore  leaf-blight,  description,  effects,  and  control 20 

mildew  injury 18 

mistletoe  injury 15 

Taphrina  caerulescens,  cause  of  leaf-blister  of  oak 21 

Tar-spot  disease,  maple,  description  and  control  by  burning  dead  leaves 19 

Thelephora  galactina,  root  fungus,  injury  to  oaks 24 

Ties,  decay  caused  by  Polystictus  versicolor,  description 53-56 

Tillandsia  spp.,  injuries  to  forest  trees 17 

Timber,  broadleaf,  sap-rot  caused  by  Polystictus  versicolor,  susceptibility 53 

cutting  season,  relation  to  decay  resistance 63 

decay,  entrance  of  fungi,  explanation 64-65 

preventive  methods 66-67 

drying  to  prevent  decay 66 

piling,  precautions 66 

structural,  decay,  causes,  rate,  prevention,  etc 60-61,  62-67 

Timbers,  composite,  use  to  avoid  dry-rot 67 

Tinder  fungus.    See  Fungus,  tinder. 

Tree  diseases,  classification 9 

trunks,  sounding  to  detect  white  heart-rot 26 

wounds,  protection  to  prevent  fungous  growth 36,  37 

Trees,  age  at  which  susceptible  to  red  heart-rot 38 

relation  to  development  of  white  heart-rot 32-33 

broadleaf,  classification  as  to  length  of  life 62 

decay  resistance 62 

fungi  causing  diseases 25-52 

sap-rot  caused  by  Polystictus  pergamenus,  susceptibility 57 

versicolor,  susceptibility 56 

timber,  rate  of  decay  of  different  woods 56,  58 

dead,  growth  of  fungi 31,  38,  42,  49,  52-61 

deciduous,  sap-rots 52-61 

destruction  by  white  heart-rot 33-34 

diseased,  removal  to  prevent  spread  of  fungi 36,  39,  47 

forest,  injuries  caused  by  cold,  wind,  and  animals 13-14 

resistance  to  sulphur-gas  injury  in  Germany 11 

susceptibility  to  sulphur-gas  injury,  list 11 

fruit,  transmission  of  fungi  from  oaks 24 

Trelease,  William,  reference  to  work 18 

Tsuga.     See  Hemlock. 

Tubeuf ,  Carl  von,  reference  to  work 49 

Tulip  poplar.     See  Poplar,  tulip, 
tree.     See  Poplar,  tulip. 

Tuzson,  J. ,  reference  to  work 61 

Ulmus  americana.     See  Elm. 

Usnea  barbata,  injury  to  trees 18 

Valsonectria  parasitica,  cause  of  chestnut  bark  disease 22 

Waite,  M.  B.,  reference  to  work 18 

149 


[NDEX.  85 

Walnut,  black,  red  heart-rot,  susceptibility 

white  heart-rot,  Busceptibility 

white.     See  Butternut. 

rot,  susceptibility 

Water,  ground,  cause  of  disease  in  certain  trees 1 :; 

Waugh,  F.  A.,  reference  to  work 

Weathering  of  timber  as  cause  of  decay 

White  heart-rot.     See  Rot,  heart,  white. 
oak.     See  Oak,  white, 
pine.     See  Pine,  white, 
rot.     See  Rot,  white. 

Willow,  heart-rot,  susceptibility 42 

leaf-rust  injury  to  osier  willow  plantations :         1!) 

mildew  injury L8 

sap-rot,  occurrence 57 

white  heart-rot,  susceptibility : 26 

rot,  susceptibility 

Wind,  injuries  to  trees 11 

Witches' broom  formed  by  mistletoe,  injuries  to  trees L6  17 

Wood,  preservation  by  chemicals  to  prevent  decay I 

rotting  fungi,  description,  progress  of  decay 5J 

structure,  effect  of  Fomes  igniarius 

Wound  fungi  causing  diseases  of  forest  trees - 

parasites 

Wounds,  tree,  importance  as  causes  of  disease 1  1.  -  1. 

protection  to  prevent  fungous  growth 

149 

O 


[Continued  from  page  2  of  cover.] 

No.  n>.  Agricultural  Explorat ions  in  Algeria.     L905.     Price,  lOcents. 

81.  Evolution  of  Cellular  Structures.     1905.     Price,  5 cents. 

82.  Grass  Lands  of  the  South  Alaska  c< .a -i.     19135.     Price,  10 
S3.  Tlie  Vitality  of  Buried  Seeds.     $05.     Price,  5. cents. 

84.  The  Seeds  of  the  Bluegrasses.    1905.     Price,  5  cents. 

Sfi.  Agriculture  without  Irrigation  in  the  Sahara  I  ><■  eri .     L905.     Price,  5  i  i 

87.  Disease  Resistance  of  Potatoes.    1905.    Price,  5  cents. 

88.  Weevil-Resisting  Adaptations  of  the  Cotton  Plant.    1906.     Price,  10. a 

89.  Wild  Medicinal  Plants  of  the  United  States.    1906.     Price,  5c< 

90.  Miscellaneous  Papers.    1903.    Price,  Scents. 

91.  Varieties  of  Tobacco  Seed  Distributed,  etc.    1906.     Price,  5  cents; 

94.  Farm  Practice  with  Forage  Crops  in  Western  Oregon,  etc.     L906.     Price,  !<■  ■ 

95.  A  New  Type  of  Red  Clover.     1903.     Price,  10  cents.  . 

96.  Tobacco  Breeding.    1907.    Price,  15  cents. 

98.  Soy  Bean  Varieties.    1907.    Price,  15  cents. 

99.  Quick  Method  for  Determination  of  Moisture  in  Grain.     1907.     Prta 
100.  Miscellaneous  Papers.    1907.     Price,  15  cents. 

10R  Contents  of  and  Index  to  Bulletins  Nos.  1  to  100.    1907.     Price,  tS  cenl 

102.  Miscellaneous  Papers.    1907.    Price,  15  cents. 

103.  Dry  Farming  in  the  Great  Basin.     19:)7.     Price,  10  cents. 

104.  The  Use  of  Feldspathic  Rocks  as  Fertilizers.    1907.     Price,  5  cents, 

105.  Relation  of  Composition  of  Leaf  to  Burning  Qualities  of  Tobacco!     Phi;.     Price,  1", 

106.  Seeds  and  Plants  Imported.    Inventory  No.  12.    1907.    Price,  15  cents. 

107.  American  Root  Drugs.    1907.     Price,  15  cents. 

108.  The  Cold  Storage  of  Small  Fruits.    1907.     Price,  15  cents. 

110.  Cranberry  Diseases.    1907.    Price,  20  cents. 

111.  Miscellaneous  Papers.    1907.    Price,  15  cents. 

112.  Use  of  Suprarenal  Glands  in  Physiological  Testing  of  Drug  Plants.     1907.     Price*  10a 

113.  Comparative  Tolerance  of  Various  Plants  for  Salts  in  Alkali  Soils.     L907.     Price,5a 

114.  Sap-Rot  and  Other  "Diseases  of  the  Red  Gum.    1907.    Price,  15  cents. 

115.  Disinfection  of  Sewage  Effluents  for  Protection  of  Public  Water  Supplies.     1907.     Price, 

116.  The  Tuna  as  Food  for  Man.    1907.    Price,  25  cents. 

117.  The  Reseeding  of  Depleted  Range  and  Native  Pastures.    1907.     Price,  10  cents. 

118.  Peruvian  Alfalfa.    1907.     Price,  10  cents. 

119.  The  Mulberry  and  Other  Silkworm  Food  Plants.    1907.     Price,  lOcents. 

120.  Production  of  Easter  Lily  Bulbs  in  the  United  States.     190S.     Price; -20  cents. 

121.  Miscellaneous  Papers.    1908.    Price,  15  cents. 

122.  Curly-Top,  a  Disease  of  Sugar  Beets.    1908.    Price,  15  cents. 

123.  The  Decay  of  Oranges  while  in  Transit  from  California.    1908.     Price,  20  cents. 

124.  The  Trickly  Pear  as  a  Farm  Crop.    1908.     Price,  lOcents. 

125.  Dry-Land  Olive  Culture  in  Northern  Africa.    190S.     Price,  10  cents. 

126.  Nomenclature  of  the  Pear.    1908.    Price,  30  cents. 

127.  The  Improvement  of  Mountain  Meadows.    1908.     Price,  lOcents. 

128.  Egyptian  Cotton  in  the  Southwestern  United  States.    1908.     Price,  L5  cents. 

129.  Barium,  a  Cause  of  the  Loco-Weed  Disease.    190S.    Price,  10  cents. 

130.  Dry-Land  Agriculture.    1908.    Price,  10  cents. 

131.  Miscellaneous  Papers.    1908.    Price,  lOcents. 

132.  Seeds  and  Plants  Imported.    Inventory  No.  13.     Kins.     Price.  21 1 . •• 

133.  Peach  Kernels,  eta.,  as  By-Products  of  the  Fruit  Industry.     1908.     Price,  5 

134.  Influence  of  a  Mixture  of  Soluble  Salts,  Principally  Sodium  Ghlorid,  upon  the  1 

Transpiration  of  Wheat,  Oats,  and  Barley.    1908.     Price,  5  • 

135.  Orchard  Fruits  in  Virginia  and  the  South  "Atlantic  States.    1808.     Pit 

136.  Methods  and  Causes  of  Evolution.     1908.     Price,  10  cents. 

137.  Seeds  and  Plants  Imported.    InventoryNo.il.    1909.     Price,- 10  cents. 

138.  Production  of  Cigar-Wrapper  Tobacco.    190S.     Price.  15  cents. 

139.  American  Medicinal  Barks.    1909.     Price,  L5  cents. 

140.  ''Spineless"  Prickly  Pears.    1908.     Price.  10  cents. 

141.  Parti.  The  Relation  of  Nicotine  to  the  Quality  oJ  Tobacco.    1908.     Pri<  • 

Granville  Tobacco  Wilt.    1.908.     Price,  5  cents. 

142.  Seeds  and  Plants  Imported.    Inventory  No.  15.     L909.     Price,  LOcents. 

143.  Principles  and  Practical  Methods  Of  Curing  Tobacco.    L909.     Price,  li  1 

144.  Apple  Blotch,  a  Serious  Disease  of  Southern  Orehan  K     1  ■in.     i 

145.  Vegetation  Affected  by  Agriculture  in  Central  A  1 

146.  Superiority  of  Line  Breeding  over  Narrow  Breeding.    1909.     Price,  1 

147.  Suppressed  and  Intensified  Characters  in  Cotton  Hybrids,    L909.     <  1 

148.  Seeds  and  Plants  Imported.    Inventory  No.  Ik    1909.     Price 

149 


mmmmmmi 


